Iranian President Hassan Rouhani said Monday that the United States would regret violating the nuclear deal, and that Iran would respond in "less than a week" if that happened. However, the USA president re-certified the deal in January but said the US would not do the same in May, when the next deadline comes up.
The nuclear agreement curbed and set caps on Tehran's controversial nuclear enrichment program in exchange for relief from global sanctions.
Iran also said it would be "humiliating" for the European countries to follow the U.S. policy on the nuclear deal, according to Press TV.
"If they breach the deal, they will see its impacts within a week or less than a week", Rouhani said.
"In case the USA 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 USA", he said without elaboration.
US President Donald Trump has threatened to walk away from the nuclear deal and reimpose sanctions by May 12 unless tough new restrictions are imposed on Iran's nuclear and missile programmes.
Iran often boasts of technological achievements which are impossible to independently verify.
"Trust your nation's powers and the power of regional nations", he said.