Tehran, April 9, Head of the Atomic Energy Organization of Iran, Ali Akbar Salehi, on Sunday warned the US against any move which undermines the 2015 landmark nuclear deal between the Islamic republic and the world powers.

"In case the US decides to walk away from the deal, Iran would be able to resume 20 percent enriched uranium in four days, Xinhua cited Salehi as saying to Iran's Parliament news agency.

Returning to the production of 20 per cent enriched uranium "bears messages for the US," he said without elaboration.

Iran has long considered the appropriate responses to the possible quit of the nuclear deal by the US, he said, adding that "we hope the Americans do not drop the deal ... since it would be a scientific challenge for them."

On Thursday, Salehi warned the US not to make any more move against the 2015 Iranian nuclear deal.

"We are seriously looking to preserve our national interests and sovereignty, but if the United States withdraws and Europe and other great powers retreat from this agreement, we will definitely do something different," said Salehi.

Salehi described US President Donald Trump as a businessman who tries to advance his international agendas with unpredictable decisions.

Trump has repeatedly demanded the elimination of sunset clauses for some of the restrictions the US places on Iran from the nuclear deal, stronger inspection rules, and limitation to Iran's development of long-range missiles.

But Iran says it will neither tolerate anything beyond its commitment to the nuclear deal, formally known as the Joint Comprehensive Plan of Action (JCPOA), nor accept changes to the agreement.

Iran also said it would be "humiliating" for the European countries to follow the US policy on the nuclear deal, according to Press TV.

Iran's atomic chief said the main responsibility of his organisation is to make preparations to deal with this scenario, adding that the organisation has already got ready in this regard.