"They have an important decision to make very soon on snapback, on the snapback of sanctions because Iran is clearly out of compliance with the current deal," he said as he left Paris after talks with European counterparts.

During his first term, US President Donald Trump withdrew the United States from a landmark nuclear deal which imposed curbs on Iran's nuclear programme in return for sanctions relief.

Tehran adhered to the deal until Washington's withdrawal, but then began rolling back its commitments.

Efforts to revive the 2015 nuclear pact have since faltered, and European officials have expressed frustrations over Tehran's non-compliance.

"Iran is out of compliance, they have to reimpose the sanctions," Rubio added.

With Trump back in office, Washington has re-engaged in the highest-level Iran-US nuclear talks since the previous accord's collapse.

The United States and Iran held discussions on Tehran's nuclear programme in Oman last weekend, without European powers.

Another Omani-mediated round is scheduled for Saturday, in Italy.

Visiting Iran on Thursday, UN nuclear watchdog chief Rafael Grossi said Tehran and Washington were running out of time to secure an accord.

Before heading to Iran, Grossi told French newspaper Le Monde that Tehran was "not far" from possessing a nuclear bomb.