Defenders of the agreement say that other provisions written into the deal are sufficient to prevent Iran from getting a weapon.
"If you simply condemn and threaten, then we're going to antagonize countries over whom we want to exert influence", said Lavrov, referring to Trump's comments.
"Ugly, ignorant words were spoken by the US president against the Iranian nation", said Rouhani in his own speech to the General Assembly, "full of hatred and baseless allegations". Secretary of State Rex Tillerson has said Iran is "clearly in default" of the accord's preamble calling for progress toward regional peace and stability. Iranians in May overwhelmingly re-elected President Hassan Rouhani, a moderate who has campaigned on the nuclear deal and better relations with the West. "America first" was one of his slogans from a campaign in which he often belittled the United Nations; he now says it has "tremendous potential".
Israeli Prime Minister Benjamin Netanyahu said the Iran nuclear deal must be amended or canceled, but suggested that scrapping the deal may be preferable.
"The exiting of the United States from such an agreement would carry a high cost, meaning that subsequent to such an action by the United States of America, no one will trust America again", Rouhani told NBC's Lester Holt in an interview set to air later Tuesday. Washington could not abide by an agreement "if it provides cover for the eventual construction of a nuclear programme", Trump said. "Frankly, that deal is an embarrassment to the United States".
"If it can not be preserved what will happen then is a very important question that we are analyzing as well as (is) the European Union", Rouhani said, and "other partners" are also analyzing and discussing scenarios.
However, although Trump does not like the deal, his speech to the United Nations on Tuesday did not mean Washington would withdraw from the pact, Nikki Haley, U.S. Ambassador to the U.N., said on Wednesday. "This is a time for statesmanship", he stressed.
Trump's meeting with Netanyahu was the first of the many world leader confabs he is scheduled to have on the sidelines of the United Nations General Assembly this week.
In Myanmar's capital of Naypyitaw, leader Aung San Suu Kyi defended the government earlier in the day and said her country does not fear global scrutiny.
"Well, I have decided", Trump said, adding that, "I'll let you know what the decision is".
At the Security Council, Pence applauded the peacekeeping reform resolution, saying all peacekeeping missions should have an exit strategy.