The Israeli defense minister tried on Friday to turn up the pressure on Hamas to release more hostages, saying Israel was preparing to seize more territory in Gaza and intensify attacks by air, sea and land if the armed Palestinian group does not cooperate.

The statement by the defense minister, Israel Katz, came days after a cease-fire that had been in place for more than two months was shattered with a renewed Israeli bombardment and limited ground operations inside Gaza. More than 500 Palestinians have been killed since Israel restarted attacks on Tuesday, according to the Gaza health ministry, which does not distinguish between civilians and combatants.

“The more Hamas persists in its refusal, the more territory it will lose,” Mr. Katz said in demanding the release of more hostages.

There were no reports of new Israelis attacks with heavy casualties in Gaza on Friday morning. Mediators were still trying to prevent the new escalation of violence from snowballing back into a full-scale war. Hamas said Friday that negotiations to return to the truce — which began in mid-January — were still ongoing.

But Hamas reiterated that any agreement to free more hostages would have to lead to a permanent end to the war, which Israel has been loath to commit to while the Palestinian militant group still is in charge of Gaza.

Over the past three days, Israeli forces have bombarded targets across Gaza, saying they were attacking Hamas sites and operatives. Israeli ground troops have seized a major corridor in central Gaza from which it withdrew during the cease-fire with Hamas, and they have expanded ground raids in northern and southern Gaza.