After talks with the remaining parties to the deal in Vienna, Iranian negotiator Seyyed Abbas Araqchi said Iran is "fully prepared" to reverse pullbacks from its nuclear commitments but only if the other side reciprocated.
"We are still open to any initiative which can ensure Iran's dividends of the JCPOA," said Araqchi, the deputy foreign minister, referring to the deal by its full name – the Joint Comprehensive Plan of Action.
"We are fully prepared to reverse steps we have taken so far in return for the fulfillment of the other side's commitments under the JCPOA."
Araqchi focused on European efforts to set up a special trading mechanism that will allow barter trade with Iran, known as INSTEX, which has yet to perform a transaction.
"It is important that we can say that the JCPOA is still alive," he said.
"We know that the Europeans are trying. We know that there is willingness but the lack of ability is obvious."
Britain, France, and Germany launched the deal's formal dispute process in January after Iran said it would no longer observe limits on the number of centrifuges used to enrich uranium – one of the deal's key stipulations.
The dispute process spells out several steps, the last one of which is notifying the UN Security Council. UN sanctions would then automatically "snap back" after 30 days unless the Security Council voted to stop it.
Iran argued on Wednesday that it needed some benefits under the deal, which promises it sanctions relief in return for curbing its nuclear program.
Renewed US sanctions have crippled the Iranian economy and were cited as the reason for Iran restarting various nuclear processes since May last year.
The European Union – which oversaw the Vienna talks between Iran, the three Western European nations, Russia, and China – said "serious concerns" had been expressed over compliance.
“Serious concerns were expressed regarding the implementation of Iran's nuclear commitments under the agreement,” the European Union’s foreign policy service's secretary general, Helga Schmid, who chaired the meeting, said in a statement.
But the EU statement added, "Participants also acknowledged that the reimposition of US sanctions did not allow Iran to reap the full benefits arising from sanctions-lifting.
“All participants reaffirmed the importance of preserving the agreement recalling that it is a key element of the global nuclear non-proliferation architecture.”
Schmid tweeted that the meeting "concluded with substantial discussions on next steps."
Mikhail Ulyanov, Russia’s representative, said the meeting was held in a "businesslike atmosphere" where participants "reaffirmed their commitment" to the Iran deal, while Iran's official news agency IRNA called the gathering the "shortest ever" JCPOA meeting.
Western diplomats believe Iran is unlikely to come back into full compliance without substantial concessions – such as an end to US sanctions or Europe taking measures to offset their economic impact.
At a major international security conference in Munich earlier this month, Iran's Foreign Minister Mohammad Javad Zarif said Tehran would be prepared to move back toward the deal if Europe provides "meaningful" economic benefits.
Europe has created INSTEX to try to enable legitimate humanitarian trade with Iran, but it has yet to complete any transactions and Tehran regards it as inadequate.
The renewed US sanctions have kept away Iran from the international financial system, driven away oil buyers and slashed Iran’s exports.
AFP and Reuters contributed to this story.