Israeli Prime Minister Benjamin Netanyahu says the Gaza war has come at a "very heavy price" for his side.
The military says 14 more soldiers have been killed in the Palestinian territory since Friday, bringing the total of the ground assault to 153.
Saturday was one of its deadliest days - but Mr Netanyahu said his forces had "no choice" but to keep fighting.
Meanwhile, the health ministry in Gaza - run by Hamas - says another 166 people were killed in the last day.
More than 20,000 people have been killed - mostly women and children, and 54,000 injured in Gaza since 7 October, the ministry says.
Remarking on the latest Israeli troop deaths, Mr Netanyahu said: "This is a difficult morning, after a very difficult day of fighting in Gaza."
But he said his forces would continue with "full force until the end", reiterating his goals of eliminating Hamas and ensuring the safe return of hostages held in Gaza.
"Let it be clear: this will be a long war," the Israeli prime minister added.
The military later said it had killed more than 8,000 Palestinian fighters during its campaign to date - in remarks quoted by the Reuters news agency.
The Israeli operation began after Hamas fighters crossed from Gaza into southern Israel on 7 October, killing 1,200 people and taking about 240 hostages.
Israel insists that it takes steps to avoid civilian casualties, and blames Hamas for embedding itself in densely-populated areas.
US President Joe Biden - a key ally of Mr Netanyahu - emphasised the "critical need" to protect civilian lives during a call with the Israeli prime minister on Saturday, the White House said.
Mr Biden told reporters that he had not asked for a ceasefire in the call. Both men believe such a move would benefit Hamas.
On Friday, the UN Security Council approved a resolution demanding large-scale aid deliveries to Gaza - but this, too, stopped short of calling for a ceasefire between the two warring sides.
Talks held in Egypt earlier this week designed to secure a fresh truce between Israel and Hamas have so far failed to deliver results.
A Palestinian official familiar with the ceasefire negotiations told the BBC that Egypt presented a new three-stage plan that would begin with a two-week humanitarian truce - which could be extended - during which Hamas would release 40 hostages and Israel would release 120 Palestinian prisoners.
This stage would be followed by the formation of an independent body to deal with humanitarian relief and reconstruction, as well as a comprehensive ceasefire and an exchange of prisoners.
The Israeli military has kept up its bombing campaign in Gaza - ordering civilians to flee. The UN said the latest evacuation order affected 150,000 people in the middle of the territory.
On Saturday, Israel said 700 Palestinian militants had been arrested during its ground offensive to date.
It also said one of its fighter jets had killed Hassah Atrash, a man it accused of smuggling weapons into Gaza to arm Hamas. There has been no confirmation from Hamas.
The Israeli military has said it has almost full operational control of the north of the Gaza Strip, and is stepping up operations elsewhere.
A spokesman has said troops are entering new Hamas strongholds in southern areas.
Briefing his cabinet on Sunday, Mr Netanyahu denied suggestions the US president had persuaded him against further expanding his military operation.
The Wall Street Journal had reported that Mr Netanyahu had been talked out of attacking Hamas's ally in Lebanon, the Hezbollah group.
A government spokesperson told the BBC "the situation in the north... is intolerable" and that Israel was "trying to deter Hezbollah from dragging us into a war".
"We will continue making the necessary preparations to repel this threat from the northern border," he added.