The hard-won deal has been threatened with collapse since the United States withdrew from it last year and reimposed biting sanctions against Iran as part of a "maximum pressure" campaign.

"It was agreed to convene an extraordinary meeting of the JCPOA joint commission in Vienna on July 28," Iran's foreign ministry said on Tuesday, using the acronym for the deal's formal name, the Joint Comprehensive Plan of Action.

The meeting would be held at the level of deputy ministers and political directors, it said in an English-language statement.

It was requested by the European parties to discuss the "new situation", the statement added, referring to Iran's reduced nuclear commitments under the deal in response to the US withdrawal.

Iran said on May 8 it would disregard certain limits of the deal as long as the remaining parties -- Britain, China, France, Germany and Russia -- fail to do more to mitigate the impact of the US sanctions, especially to sell its oil.

Tehran has also threatened to take further measures.

It has since exceeded limits the deal had set on its enriched uranium and heavy water stockpiles, as well as passing a cap the deal had imposed on its uranium enrichment.

The 4.5 percent enrichment level it reached is well below the more than 90 percent required for a nuclear warhead.

Iran has yet to specify what further steps it may take, and has repeatedly emphasised that its actions can be reversed "within hours" if European partners deliver on their commitments.