"But opportunities have been lost, and the counterparts have been unable to live up to their commitments in the JCPOA, in a way that Iran is left no way but to reduce its commitments", the news agency said, adding that Rouhani´s letter would be a "political" one. Zarif said the remaining countries had a "narrowing window" to save the deal.
Mr Zarif said the move was in response to American withdrawal from the JCPOA saying that Washington's attempts under the Trump administration were aimed at derailing the deal.
On Sunday, Secretary of State Mike Pompeo issued a warning to the Islamic Republic.
On May 8, 2018, US President Donald Trump pulled his country out of the JCPOA.
The deployment of a U.S. aircraft carrier strike group and a bomber task force to the U.S. Central Command region of responsibility represented "a prudent repositioning of assets in response to indications of a credible threat by Iranian regime forces", Shanahan tweeted Monday.
This surgery is to save the deal, not destroy it. Ultimate authority in Iran is in the hands of Supreme Leader Ali Khamenei, a cleric in power since 1989, who signed off on the nuclear deal but remains close to the hardline faction that challenges Rouhani.
Iran reached the deal with world powers in 2015 after years of negotiations, including secret talks between Iran and President Barack Obama's administration in Oman.
Washington's European allies say Trump's repudiation of the deal hurts the pragmatic wing of Iran's leadership and plays into the hands of hardliners. Such reactors produce plutonium that can be used in nuclear weapons.
Tit-for-tat: Timeline of US-China trade dispute
As late as last Friday, the signs of signing off on a deal looked promising, according to US Treasury Secretary Steven Mnuchin. Trump appeared to defend his decision in a tweet early on Monday, lashing out over the US trade deficit with China.
In a speech broadcast on national television, Rouhani said he had written to the remaining signatories saying Tehran would start rolling back on its commitments by stopping selling enriched uranium and heavy water to other nations.
"Iran's future actions will be fully within the (nuclear deal), from which the Islamic Republic will not withdraw", Zarif said, according to state media.
The U.S. announced last week it would no longer waive sanctions against countries that buy Iranian oil - another blow to Iran. However, their efforts have largely failed, with all major European companies abandoning plans to do business with Iran for fear of US punishment.
The 2015 deal lifted sanctions on Iran in exchange for limits on its nuclear program.
Sergey Lavrov criticized the USA during a meeting with his Iranian counterpart Javad Zarif, who personally brought a letter from his government informing Russian Federation about Tehran's latest decision on the nuclear agreement.
Iranian officials had warned that the country might increase its uranium enrichment, potentially pulling away from the deal after spending a year trying to salvage it with European partners.
United Nations inspectors said Iran had continued to comply with the deal after the US withdrawal.
US West Texas Intermediate (WTI) crude futures were at $61.90 per barrel at 4.51am GMT on Wednesday, 80 cents, or 0.8 percent, above their last settlement, Reuters reported. That is an 11 percent rise from the same month past year.