Israeli Prime Minister Benjamin Netanyahu on Sunday ruled out the prospect of an immediate cease-fire with the Palestinians in the deadly flare-up of Middle Eastern violence, defying growing international demands for de-escalation and concerted mediation efforts by regional and world powers.

Civilian casualties mounted a week after fighting intensified, with at least 42 people killed in an apartment complex attack overnight, Palestinian officials said, the deadliest in seven days of an Israeli military operation. First responders in central Gaza City could be seen pulling bodies from the rubble as they searched for survivors and screams emanated from beneath the wreckage.

In Gaza, 192 people, including 58 children and 34 women, have been killed since Monday, according to the Palestinian health ministry. In Israel, 10 people, including one child, have been killed, according to Israel’s emergency response service. Israel has said that it has killed at least 75 Hamas militants. Hamas has fired more than 2,900 rockets at Israel since Monday.

New strikes were reported early Monday morning in Gaza City. The Israeli military’s Twitter account said fighter jets targeted terrorist sites in what the Associated Press described as heavy airstrikes.

Mr. Netanyahu said Sunday that the Israel Defense Forces are seeking to degrade Hamas and its missile capabilities, and that operations wouldn’t be called off until that had been accomplished.