JERUSALEM — Mitt Romney offended Palestinian leaders on Monday by suggesting that cultural differences explain why the Israelis are so much more economically successful than Palestinians, thrusting himself again into a volatile issue while on his high-profile overseas trip.

His remarks drew a pointed rebuke from the Palestinian leadership, which angrily noted that Mr. Romney had failed to mention the years of trade restrictions imposed by Israel.

The comments came after he questioned London’s preparations for the Olympic Games while in that city, drawing criticism from the British prime minister and others. And they once again overshadowed a trip that was designed to show his dexterity on the foreign policy front, as his remarks put him in the choppy crosscurrents of Israel-Palestinian affairs where American presidents have often served as mediators.

This time, Mr. Romney did not seek to recalibrate his remarks, as he did in Britain, and the comments, made at a fund-raiser with prominent Jewish-American backers, came as he has been trying to show his fealty to the Israeli cause and slice into President Obama’s Jewish support.