JERUSALEM—Prime Minister Benjamin Netanyahu said the new war plan approved by Israel’s security cabinet includes dismantling Hamas in Gaza’s central refugee camps in addition to Gaza City, a broadening that comes as he faces criticism internationally for expanding the war and from the far-right wing his coalition for not going far enough.

The new war plan was approved just ahead of the weekend. An announcement by the prime minister’s office at the time only mentioned that the military would prepare to take over Gaza City. Netanyahu revealed the previously undisclosed targeting of the central camps in comments to reporters Sunday.

The more limited initial objectives announced last week—after Netanyahu had touted a takeover of the entire Gaza Strip—were criticized by far-right Finance Minister Bezalel Smotrich as too incremental.

“They decided once again to do the same thing and head for a military campaign that doesn’t aim for decisive victory, but just pressuring Hamas to go for a partial hostage deal,” Smotrich said in a video statement on Saturday.

“Unfortunately, for the first time since the start of the war I feel I cannot stand behind this decision and back it,” Smotrich said, adding that he had lost confidence that Netanyahu wanted to defeat Hamas.

Israel also came under heavy pressure internationally over its decision to expand the war as well as earlier moves that sharply restricted the flow of food into Gaza and pushed many Palestinians closer to starvation. Germany said last week that it would restrict arms sales to Israel, while European countries and the U.K. criticized the war plan.

The prime minister’s ruling coalition relies on the support of far-right lawmakers like Smotrich and National Security Minister Itamar Ben-Gvir. Netanyahu has had to balance their demands with the views of his military and pressure from international partners since the beginning of the war in Gaza, which was sparked by Hamas’s deadly attack on Israel nearly two years ago.

“Last Thursday, Israel’s security cabinet instructed the IDF to dismantle the remaining Hamas strongholds in Gaza city and the central camps,” Netanyahu said, during a news conference for foreign journalists, referring to the acronym for the Israeli military.

Netanyahu offered few details of the new plan or how the central camps would fit into it on Sunday. He said the military would evacuate the population before the assault to “designated safe zones,” where they would be provided with humanitarian aid. He declined to provide a timeline for the operation, but said Israel hoped to complete it quickly so it could end the war

Israeli authorities say it will begin with the goal of seizing control of Gaza City—the biggest population center in the north of the strip. Military analysts said it could play out over weeks or months, reflecting serious resource constraints that are likely to limit the pace and scope of military operations.

Under the plan, hundreds of thousands of Palestinians face the prospect of further displacement and new rounds of deadly fighting. More than 60,000 people have been killed in Gaza during the war, according to Palestinian health authorities, who don’t say how many were combatants.

Some analysts said Israel appears to hope the increased military pressure will bring Hamas back to the negotiating table on its terms and could pause the operation at any point.

Israel says it currently controls up to 75% of the Gaza Strip. Around two million Gazans are crammed into Gaza City, the seaside tent encampment at Al-Mawasi, and the central camps. Invasion of those areas would squeeze the population to an ever shrinking territory amid a worsening humanitarian crisis.

The new plan will require the country to call up a large number of soldiers. The military already faces severe manpower strains, and reservists are exhausted from almost two years of war in Gaza, Syria, Lebanon and the West Bank.

Polls in Israel have shown for months that a large majority of the population, including right-wingers, support ending the Gaza war in exchange for freedom for the remaining hostages held by Hamas.

Tens of thousands of Israelis took to the streets of Israel on Saturday to protest Netanyahu’s expansion of the war, in one of the largest antiwar demonstrations in recent months.

Write to Anat Peled at anat.peled@wsj.com