With those decisions, he said, “this administration has reneged on all previous U.S. commitments, and has undermined the two-state solution, and has revealed its false claims of concern about the humanitarian conditions of the Palestinian people.”

Speaking about the new Israeli law that makes the right of national self-determination “unique to the Jewish people,” Mr. Abbas said it reminded him of laws in “the apartheid state that existed in South Africa.”

Mr. Netanyahu angrily rejected the analogy when it was his turn to speak. He also denounced critics who assert Israel cannot be Jewish and democratic. “This is false,” Mr. Netanyahu said. “Israel is both, Israel will always remain both.”

The Israeli prime minister also assailed Mr. Abbas for policies he said encourage attacks on Jews.

“President Abbas, you proudly pay Palestinian terrorists who murder Jews,” Mr. Netanyahu said. “In fact, the more they slay, the more you pay. And you condemn Israel’s morality, you call Israel racist? This is not the way to peace.”

Their speeches came a day after Mr. Trump, following a meeting with Mr. Netanyahu on the sidelines of the General Assembly, told reporters that he would release his peace plan within four months and that he preferred a two-state solution. “That’s what I think works best,” he said. “That’s my feeling.”

The statement differed from what Mr. Trump had said previously — that he would support a two-state solution if both sides agreed to it, but that he also did not rule out a different path.

Mr. Netanyahu has for years avoided referring to a two-state solution in public, partly to avoid antagonizing political allies in Israel who reject that idea.