Airstrikes killed a number of soldiers near the northern Syrian city of Aleppo early Friday, Syria’s state news media and an independent organization reported, in what appeared to be one of the heaviest Israeli attacks in the country in years.

The Syrian Observatory for Human Rights, a Britain-based group that tracks Syria’s civil war, said that the dead included 36 Syrian soldiers, seven Hezbollah fighters and a Syrian from the pro-Iranian militias. The group said the attack appeared to have hit multiple targets, including a weapons depot belonging to Hezbollah, a Lebanese militia that Iran supports and has a presence in Syria.

The airstrikes stoked fears that have unsettled Western officials for months: that Israel’s war against Hamas in Gaza could escalate into a broader conflict against Syria, Iran and its proxies across the region, which could entangle allies of those involved, like Russia and the United States.

American officials have sought to tamp down tensions, and Iran has tried to rein in its network of militias after a drone fired by one of the groups killed three U.S. Army reservists in January. But fears of a wider conflict have persisted as Israel and Hezbollah have clashed for months along the border, and as Israel has carried out assaults on Iran-linked targets in Syria.

Israel’s military did not immediately comment on the Syria strikes on Friday, but its defense minister, Yoav Gallant, appeared to hint at responsibility.

“We will pursue Hezbollah every place it operates and we will expand the pressure and the pace of the attacks,” he said on social media, promising more operations in Lebanon, Syria and “other more distant locations.”

Iran supports and arms a network of proxy militias that have been fighting with Israel, including Hamas, whose political leader was in Iran for high-level meetings this week. Attacks across the borders of Lebanon and Syria have escalated since Oct. 7, when Hamas led a sweeping raid into Israel and the country responded with an intense bombardment and later ground invasion of Gaza.

The Israeli military said this month that its forces had struck more than 4,500 Hezbollah targets in Syria and Lebanon since Oct. 7. The assaults, it said, had killed over 300 Hezbollah members, though that could not be independently confirmed. Hezbollah’s official website and spokesman said that “more than 200” of its fighters had been killed to date.

On Friday, Syria’s state-run official news agency, SANA, did not specify a death toll in what it identified as an Israeli attack. It said several civilians and soldiers had been killed or wounded in strikes on multiple locations near Aleppo around 1:45 a.m.

In a separate incident, the Lebanese state news media reported that an Israeli drone strike had targeted a car in southern Lebanon, killing at least one person.

The Israeli military confirmed that it had carried out that strike, which it said had killed the deputy commander of Hezbollah’s rocket and missile unit. Hezbollah acknowledged the death of the man, Ali Abdulhassan Naim, on Telegram but did not elaborate on the circumstances.

Mr. Gallant, the Israeli defense minister, praised the strike, calling it “another successful assassination of a Hezbollah commander.”

The Israeli military and Hezbollah have been exchanging fire across the border for months, displacing tens of thousands of Lebanese and Israelis from their homes.

On Thursday, the United Nations peacekeeping mission deployed along the border said in a statement that it was very concerned about the surge in violence, which has killed many civilians and destroyed homes and livelihoods.

Israel has come under increasing international pressure over the Gaza war in recent days: On Monday, the U.N. Security Council passed a resolution calling for an immediate cease-fire, and on Thursday the top U.N. court ruled, in its sharpest language yet, that Israel must ensure the “unhindered delivery of assistance” to Gaza.

Prime Minister Benjamin Netanyahu of Israel on Friday authorized a delegation to travel to Qatar and Egypt in the coming days for talks on a possible cease-fire. But it remained unclear whether Israel would reschedule another delegation’s trip to Washington, as the White House said it was trying to do, following Mr. Netanyahu’s decision to hold the team back in response to the U.S. abstention from the Security Council vote.

In response to the U.N. court ruling, Israel on Friday said it was committed to its legal obligations to provide aid to Gazan civilians, and that it would promote “new initiatives” to do so. Israel has endorsed a handful of aid efforts in the last month, including a ship carrying food from Cyprus, airdrops by foreign countries and crossings into northern Gaza by a small number of aid trucks.

But progress on the efforts to ramp up deliveries has been slow, and aid groups say the current level is not nearly sufficient to meet the vast need in the enclave.

Despite the growing pressure over the humanitarian crisis in Gaza, Israeli leaders have vowed to keep pursuing their objective of destroying Hamas, in Gaza and outside it.

Israel has already targeted Hamas officials outside the territory, most notably assassinating Saleh al-Arouri, a top Hamas leader, in early January in an explosion in a Beirut suburb, according to officials from Hamas, Lebanon and the United States. Israel has not taken responsibility for his killing.

Since the outbreak of Syria’s civil war in 2011, Israel has conducted strikes and targeted killings in the country, which Israeli officials have said are aimed at crippling the military capabilities and supply lines for Iranian-backed proxy forces.

Throughout the war, Iran and Hezbollah have backed Syria’s authoritarian president, Bashar al-Assad, with fighters and military support. Israel views the influence and military buildup of these forces as a threat to its northern border.

In a further complication for Israel, Russia also supports Mr. al-Assad. Mr. Netanyahu needs the good will of President Vladimir V. Putin to help constrain Iran and continue to strike targets in Syria, while trying to avoid harming the forces Russia maintains there.

A spokeswoman for Russia’s Foreign Ministry, Maria Zakharova, condemned the strikes on Friday, calling them “a gross violation” of Syria’s sovereignty and international law, according to the Russian state news agency Tass. The strikes, she said, were “fraught with extremely dangerous consequences” in context of the Israeli-Palestinian conflict.

Russia and Israel’s relations have already been strained by the war, and Mr. Putin has emerged as a vocal critic of Israel. His ambassador to the United Nations, Vasily Nebenzya, told the Security Council last week that Russia was guided by “what is necessary for the Palestinian people and what helps to advance peace.”

Friday’s bombardment was at least the second deadly assault in Syria in less than a week. On Tuesday, airstrikes in eastern Syria killed several people. The Iranian state news media said that Israel was responsible, while Syria’s state news agency attributed it to American forces. A Pentagon spokeswoman denied that the United States had carried out the strikes.

The Tuesday strikes killed a member of Iran’s Islamic Revolutionary Guards Corps, according to Iranian state news media reports. An engineer with the World Health Organization was also killed in the strikes, the agency said.

Johnatan Reiss and Adam Rasgon contributed reporting.