The Israeli army has warned that "fighting will intensify" even as the death toll in both Israel and Gaza continue to climb.
"We have sustained extremely heavy casualties... This, however, will not deter us and it will not weaken our resolve," said the Spokesperson Lt Col (res) Jonathan Conricus in a video update.
He added that he hoped support for Israel would continue even once fighting intensified.
"We hope that remains that way even when the fighting will intensify and the scenes coming out of the Gaza Strip will be more difficult to understand and cope with," he said.
The death toll in Israel has reached 1,200, while more than 900 people have been killed in retaliatory air strikes in Gaza
US President Joe Biden has described Hamas' assault on Israel - launched on Saturday - as an "act of sheer evil".
The first US plane carrying arms for Israel has arrived in the south of the country.
Details of a massacre in an Israeli village where fighting continued until Tuesday morning have emerged - with an Israeli general speaking of babies killed in their bedrooms.
Israeli soldiers also told BBC International Editor Jeremy Bowen that some of the dead had been beheaded.
At least 30 people have died in Israeli airstrikes overnight, a Hamas spokesperson has said.
Israeli forces said they attacked 200 targets in Gaza on Tuesday night.
