Prime Minister Benjamin Netanyahu of Israel insisted on Saturday that Israel would not bow to international pressure to call off its plan for a ground invasion of Rafah, the southernmost city in Gaza that is now packed with more than a million Palestinians.

Many of the people now in Rafah are displaced and living in schools, tents or the homes of friends and relatives, part of a desperate search for any safe refuge from Israel’s military campaign, which has dragged on for more than four months. Their lives are a daily struggle to find enough food and water to survive.

“Those who want to prevent us from operating in Rafah are basically telling us: Lose the war,” Mr. Netanyahu said at a news conference in Jerusalem on Saturday evening. “It’s true that there’s a lot of opposition abroad, but this is exactly the moment that we need to say that we won’t be doing a half or a third of the job.”

About the same time as Mr. Netanyahu addressed the news conference, thousands of anti-government protesters filled a central thoroughfare in Tel Aviv — the largest protest against the prime minister in months. They filled the same street where mass protests against Mr. Netanyahu’s efforts to weaken the country’s judiciary riled the nation before the start of the Israel-Hamas war.

Calls for an immediate election rose above a din of air horns. Protesters lit a red flare in the middle of a drum circle while others wielding flags stared down half a dozen police officers on horseback.

“The people need to rise up, and the government needs to go,” said one protester, Yuval Lerner, 57. Mr. Lerner said that even before the war, he lost confidence that the government has the nation’s best interest at heart, but “Oct. 7 proved it,” he said.

Mr. Netanyahu’s comments also came as world leaders and international organizations were raising alarms that an invasion of Rafah would only compound the humanitarian disaster for displaced Palestinians.

Josep Borrell, the European Union’s top diplomat, reiterated on Saturday his appeal to Israel to refrain from launching a military operation in Rafah “that would worsen an already catastrophic humanitarian situation.”

Mr. Netanyahu, however, said Palestinians would be permitted to leave Rafah and contended that there was “a lot of space” north of the city where civilians could resettle.

The Israeli leader played down the chances of a quick breakthrough in indirect talks with Hamas on a cease-fire in exchange for a hostage release. He said that Hamas — the armed group that long controlled Gaza and which led the Oct. 7 attack on Israel that started the war — was making “ludicrous” demands in those negotiations.

Explaining his decision to stop Israeli officials from participating in follow-up negotiations in Cairo earlier this week, the prime minister went on to say Hamas had not compromised on its demands “one nanometer.”

“There’s nothing to do until we see a change,” he added.

Earlier on Saturday, Ismail Haniyeh, the leader of Hamas’s political wing, issued a statement accusing Israel of “procrastinating” in addressing Hamas’s demands. Hamas has been calling for a comprehensive cease-fire, the reconstruction of Gaza, the end of Israel’s blockade of the territory and the release of Palestinian prisoners held by Israel.

President Biden told a news conference on Friday that he didn’t expect Israel to invade Rafah while efforts to free the hostages were ongoing.

South Africa this week asked the International Court of Justice, the United Nations’ top judicial body, to intervene to stop Israel’s planned advance into Rafah. But on Friday, the court declined to issue new constraints aimed at preventing such an incursion.

Instead, it said the “perilous situation” in Gaza, including in Rafah, required Israel to abide by its previous ruling last month, which included taking “all measures within its power” to prevent the crime of genocide by its forces.

Mr. Netanyahu has called the charge that Israel has engaged in genocide “false” and “outrageous.”

Israeli officials have insisted that an incursion into Rafah is needed to destroy tunnels between Egypt and Gaza and to try to root out Palestinian militants there. But the Israelis have not yet presented a plan to evacuate civilians as the U.S., Israel’s closest ally, has demanded.

Many civilians sheltering in Rafah have already moved multiple times as Israel’s military campaign has pushed farther south, and some have said their homes north of the city have been destroyed and they have grown tired of repeatedly relocating.

“If they want to come here — amid all these people — there will be massacres,” said Khalil el-Halabi, 70, one of the many displaced Palestinians from northern Gaza who have sought shelter in Rafah.

Some displaced Palestinians have now moved back north toward Deir al Balah in central Gaza, according to the U.N.’s humanitarian coordinator.

People in Rafah have grown so desperate for food that they are stopping aid trucks and eating what they manage to get on the spot, according to the United Nations.

Ahmad al-Ghazaly, 26, another displaced Palestinian in Rafah, said he was sheltering in a tent with his parents, both of whom he said had chronic illnesses. He said that he hoped to get permits for both of them to leave for Egypt via the Rafah border crossing, but that the process had become even more difficult and costly in recent weeks.

“It’s been four months in which we’ve barely slept, eaten, showered, and there’s constant bombardment,” Mr. al-Ghazaly said. “We’re living in conditions, I’m sorry to say, that are barely better than those of animals.”

As the Israeli invasion of Rafah looms, neighboring Egypt has grown increasingly concerned that an Israeli operation in the city could send Palestinian refugees streaming into its territory. Egypt has warned Israel of “dire consequences” should Israeli forces embark on a ground operation in Rafah.

But Israel’s defense minister, Yoav Gallant, tried to assuage those concerns on Friday, saying Israel had “no intention of evacuating Palestinian civilians to Egypt.”

Israel and Egypt have had a decades-long peace treaty that is a cornerstone of stability in the Middle East.

In recent weeks, Egypt has reinforced the border with Gaza in what some analysts have seen as a response to fears of an influx of Palestinians pouring in. A contractor and an engineer told The New York Times recently that they had received a government commission to build a concrete wall five meters high (about 16 feet) to close off a five-kilometer-square plot of land on the Egyptian side of the Gaza border in Rafah.

Speaking at the Munich Security Conference, Foreign Minister Sameh Shoukry of Egypt said his country strongly opposed any attempt to expel Palestinians to Egyptian territory and did not intend to provide “safe areas” for Palestinian refugees. But if such a situation arose, he added, the Egyptian authorities would act with “the humanity that is necessary” and provide “support to innocent civilians.”

Adam Sella contributed reporting from Tel Aviv.