The United Nations’ nuclear watchdog says Iran is honoring its commitments under the nuclear agreement it reached with world powers in 2015 a day after US President Donald Trump pulled Washington out of the landmark deal in defiance of international warnings.

The European Union (EU)'s foreign policy chief has reiterated its support for the 2015 Iran nuclear deal, saying it "regrets" US President Donald Trump's decision on Tuesday to withdraw his country from the agreement.

"US decision to leave the Iran nuclear agreement, known as the Joint Comprehensive Plan of Action (JCPOA), was a mistake," French President Emmanuel Macron stressed.