Iranian President Hassan Rouhani vowed that his country would not be the first to violate the Iranian nuclear agreement and said that he does not expect the US to abandon the 2015 deal.
He also ruled out the idea of renegotiating the pact.
"Either the nuclear deal remains as it is or it will collapse," he told reporters on the sidelines of the United Nations General Assembly gathering of world leaders.
He had earlier called President Donald Trump as a "rogue newcomer to the world of politics", a day after the US President excoriated Iran in his debut address at the United Nations General Assembly.
Shortly afterwards, Mr Rouhani said in his speech to the general assembly that Iran "will not be the first country to violate the agreement but it will respond decisively and resolutely to its violation by any party".
The Iranian leader added: "By violating its international commitments, the new US administration only destroys its own credibility and undermines international confidence in negotiating with it or accepting its word or promise."
Mr Rouhani noted that the deal, known formally as the 2015 Joint Comprehensive Plan of Action, was the outcome of two years of intensive multilateral negotiations and overwhelmingly applauded by the global community. It belongs to the international community and not only one or two countries, he added.
"It will be a great pity if this agreement were to be destroyed by rogue newcomers to the world of politics. The world will have lost an opportunity," he said.
Without mentioning Mr Trump by name, Mr Rouhani hit out at the US leader's speech on Tuesday: "The ignorant, absurd and hateful rhetoric filled with ridiculously baseless allegations uttered yesterday was... unfit to be heard at the United Nations."
In his speech, Mr Trump had accused Iran of exporting terror and instability and pursuing nuclear weapons under the cover of the Iran nuclear deal. He also hinted that the United States may pull out of the deal.
Yesterday, Mr Trump said "I have decided", when asked on the sidelines of the UN General Assembly if he had made a decision on the Iran deal, but did not elaborate.
Under the agreement signed by the US as well as the permanent members of the UN Security Council and the European Union, Iran agreed to divert its nuclear research and production to peaceful uses.
The latest assessment found that Iran has abided by the agreement.
Mr Rouhani also took a swipe at Israel, saying it was "reprehensible that the rogue Zionist regime that threatens regional and global security with its nuclear arsenal and is not committed to any international instrument or safeguard has the audacity to preach to peaceful nations".
