President Trump said that Prime Minister Benjamin Netanyahu would not be arrested in the United States, “in any way, shape, or form,” saying Mr. Netanyahu was fighting the Islamic Republic of Iran and that Iranian leaders are the ones that should be arrested.

His comments, posted on social media, came after Israel’s ambassador to the United Nations on Monday fired back at New York City’s mayor, Zohran Mamdani, who has said he is looking into whether he can arrest Mr. Netanyahu, when he visits the U.N. headquarters in September.

The “threat is empty,” the ambassador, Danny Danon, said in an address to the U.N. General Assembly. Mr. Danon said there is “no legal basis” for an arrest and he accused the mayor of engaging in “political theater” to excite his “radical base.”

When Mr. Mamdani was campaigning for mayor, he had pledged to arrest Mr. Netanyahu on his annual visit to the U.N. General Assembly this September. It would be based on an International Criminal Court warrant citing alleged war crimes and crimes against humanity in connection with the war in Gaza, following the Oct. 7, 2023, Hamas-led attack on Israel.

That warrant was issued in 2024. Mr. Netanyahu and Israel’s former defense minister, Yoav Gallant, were accused of having “intentionally and knowingly deprived” Gaza’s population of food, water, fuel and medicine, which they have denied.

In an interview with The New York Times published on Saturday, Mr. Mamdani said he was in “an active conversation” with the city’s Law Department on whether he had the authority to arrest the Israeli leader while he was visiting the U.N.