Britain, France and Germany launched a process last week charging Iran with failing to observe the terms of the 2015 deal curtailing its nuclear programme, while Tehran accuses the bloc of inaction over US sanctions, AFP reported.
The EU three insisted they remained committed to the agreement, which has already been severely undermined by the US exit from it in 2018 and its reimposition of unilateral sanctions on key sectors of Iran's economy.
"What the three European countries did regarding Iran's nuclear issue... is unfortunate," parliamentary speaker Ali Larijani was quoted as saying by state news agency IRNA.
"We clearly announce that if Europe, for any reason, uses Article 37 of the nuclear agreement unfairly, then Iran will make a serious decision regarding cooperation with the agency," he said, referring to the International Atomic Energy Agency (IAEA).