The Iranian foreign minister has met officials in Brussels, amid continued uncertainty over the US role in the agreement
The European Union has assured Tehran it remains committed to the Iran nuclear deal, insisting that the agreement is working.
The Iran deal - officially called the Joint Comprehensive Plan of Action (JCPOA) - was agreed in 2015 between Iran and various world powers, including the US, China, Russia and the EU.
As part of the deal, the Iranian government agreed to limit its nuclear programme, with the other parties agreeing to lift sanctions on the country in return.
UN officials have repeatedly found that Iran is sticking to the agreement.
EU officials and the German, French and British foreign ministers earlier met Iranian Foreign Minister Mohammad Javad Zarif in Brussels to stress their determination to keep the deal in place.
The meeting comes amid continued uncertainty on the Trump's administration's plans regarding the international agreement.
Donald Trump has of deadline of tomorrow to decide whether he will reimpose sanctions suspended under the 2015 deal.
Speaking after today's meeting in Brussels, the EU's foreign affairs chief Federica Mogherini said: "The deal is working. It is delivering on its main goal which means keeping the Iranian nuclear programme in check and under close surveillance.
"The [UN's International Atomic Energy Agency] has confirmed in nine reports that Iran is fully complying with the commitments made under the agreement, and its continued successful implementation ensures that Iran's nuclear programme remains exclusively peaceful."
She added: "At a time of acute nuclear threat, the EU is determined to preserve the JCPOA as a key element of the international non-proliferation architecture. The EU remains committed to support the full and effective implementation of the agreement."
She noted that while EU leaders have concerns about matters involving Iran, those issues are "outside the scope of the nuclear agreement". She also said the leaders had discussed the recent unrest within Iran itself.
President Trump has previously described JCPOA as one of the "worst and one-sided" agreements America has ever entered in to.
Last year, he refused to recertify the deal - but stopped short of scrapping it completely.