Iran: US would 'regret' withdrawing from nuclear deal

"We will not be the first to violate the accord, but they should definitely know that they will regret it if they violate it," Rouhani said in a conference in Tehran marking National Nuclear Technology Day.

"We are much more prepared than they think, and they will see that if they violate this accord, within a week, less than a week, they will see the result."

President Donald Trump previously issued a final warning that the US would walk away from the nuclear deal and reimpose sanctions by May 12 if new restrictions are not placed on Iran's nuclear and missile programmes.

On Sunday, Iran's currency fell more than six percent against the US dollar, hitting another record-low, as the exchange rate spiraled downwards driven by fears of the US withdrawal.

There have been long queues outside exchange offices for weeks in Iran, as uncertainty over the future of the P5+1nuclear deal looms. 

Rouhani dismissed the threat, saying: "It has been 15 months since this gentleman who came to power in America has been making claims and there have been many ups and downs in his remarks and his behaviour.

"(But) the foundations of the JCPOA (nuclear deal) have been so strong that during these 15 months of pressure ... the structure has remained solid."

Trump has repeatedly threatened to rip up the Iran nuclear agreement, a deal signed under predecessor Barack Obama. 

Other partners in the nuclear agreement include Britain, France, Germany, China, Russia and the EU.

All partners, including the International Atomic Energy Association, tasked with inspecting Iran's compliance, agree that Iran has stuck by its commitments.