A senior Foreign Ministry official said even if the recent legislation passed in the US House of Representatives aimed at blocking US purchases of heavy water from Iran gets through the Senate and survives a presidential veto, it would be "no big deal".
"The legislation, even if finalized, is no big deal," Abbas Araqchi told state television on Friday.
The 251-168 vote on the measure came as an amendment introduced by Senator Ron DeSantis to a funding bill for the US Energy Department in a House meeting on Wednesday night.
Last month, the administration of President Barack Obama completed an $8.6 million deal to buy 32 tons of heavy water from Iran.
The measure has yet to face a Senate vote and Obama's veto, Araqchi said, predicting that it is doomed just as "the last attempt in the Senate to scrap the heavy water sale ended in failure."
A similar amendment died in the Senate after a major dust-up earlier this year, when Democrats filibustered a companion proposal by freshman Senator Tom Cotton, AP reported.
The amendment would not affect last July's agreement between Iran and major powers, formally known as the Joint Comprehensive Plan of Action, but would thwart purchases next year.
Under the action plan, Iran is allowed to use heavy water in its modified Arak nuclear reactor, but must sell any excess supply of both heavy water and enriched uranium on the international market.
"Basically, the JCPOA has not committed the United States or any other country to buying Tehran's heavy water," the head of the Foreign Ministry's office for the implementation of the nuclear accord said.
"Iran's only obligation is to sell its excess supplies of heavy water on the global market. It does not matter whether we find a buyer or not," he said, noting that heavy water is a valuable product which is in high global demand.
