"We are confident that the UK, France and Germany -- indeed, all civilized nations -- will take decisive actions to stop Iran's nuclear extortion," Pompeo, who visited the European Union headquarters in Brussels earlier in the week, wrote on Twitter.

Iran has been negotiating with European powers that hope to salvage the 2015 nuclear accord despite the withdrawal last year by the United States, which reimposed punishing sanctions.

Iranian President Hassan Rouhani said Wednesday that Tehran would step up research and development work and the head of the country's atomic energy organization is set to hold a press conference on Saturday.

Iran said it would fully adhere to the deal if it sees economic relief, such as a greater ability to sell its oil -- banned through unilateral US sanctions -- or a credit line mulled by France.

Iran is hoping to air its frustrations by taking symbolic small steps to reduce compliance with the 2015 deal, in which it sharply curtailed its nuclear work in return for promises of sanctions relief.

Pompeo accused Iran, which said the new research and development would focus on centrifuges, of seeking to build "their nuclear weapons systems."

"Those things are unacceptable," Pompeo told Kansas City radio station KCMO.

Despite his administration's hawkish stance, President Donald Trump has said he is willing to speak with Iran, a prospect proposed by France.

"For months now President Trump has said that he'd be happy to meet with Iranian leadership with no preconditions. But our outcome from those conversations is also unambiguous," Pompeo, who was visiting his home state of Kansas, said in the radio interview.

In addition to ending the nuclear steps, Pompeo said the United States wanted Iran to end its "terror campaigns" through proxy groups and its development of missiles.