Secretary of State Marco Rubio was to depart for Israel on Saturday amid signs that President Trump was growing frustrated about Prime Minister Benjamin Netanyahu’s unrelenting campaign against Hamas prolonging the war in Gaza.

Mr. Rubio will land in Israel on Sunday as its military prepares for a major offensive in Gaza City. His visit comes days after an audacious Israeli airstrike targeted Hamas officials in Qatar. Arab and European officials have said that the attack would make ending the conflict even harder.

Mr. Trump told reporters this week that he was “very unhappy” about the Israeli strike in Doha, Qatar’s capital, saying that it “does not advance Israel or America’s goals.”

Mr. Trump has promised to broker an end to the nearly three-year Gaza conflict, and earlier this month submitted a fresh cease-fire proposal, which he said Israel had accepted.

But the fighting has raged on. For that, Mr. Trump and Israel blame Hamas, saying that the Palestinian militant group negotiates in bad faith. Mr. Netanyahu’s critics say he has willingly prolonged the war, prioritizing the dismantling of Hamas over the release of some 20 Israeli hostages who remain in Gaza.

Mr. Trump has done little to press Mr. Netanyahu to reach terms with Hamas, apart from his sporadic demands that Israel allow more aid into Gaza to prevent mass famine.