Vienna: The UN nuclear watchdog International Atomic Energy Agency (IAEA) has again confirmed that Iran has been implementing the Iran nuclear deal under the robust nuclear verification regime.

IAEA Director General Yukiya Amano said on Friday that Tehran was co-operating with the agency to implement the commitment to be undertaken by Tehran, Xinhua news agency reported.

"Iran is now provisionally implementing the Additional Protocol to its Comprehensive Safeguards Agreement with the IAEA, a powerful verification tool which gives our inspectors broader access to information and locations in Iran," said Amano.

Under the Iranian nuclear deal reached in 2015, IAEA is asked to verify if Iran meets its commitment to scale back its nuclear program and gives more transparency of its atomic plan.

"As I have reported to the Board of Governors, the nuclear-related commitments undertaken by Iran under the JCPOA are being implemented," he said.

US President Donald Trump has condemned Iran as a "fanatical regime" and refused to continue certifying an international nuclear deal.

Trump said on Friday he was referring the deal to Congress and would consult allies on how to alter it, BBC reported.

He accused Iran of sponsoring terrorism and said he would deny the regime "all paths to a nuclear weapon".

Reacting to it, Iranian President Hassan Rouhani said Trump cannot decertify Iran's international nuclear deal "unilaterally".

"Iran's nuclear deal is a multilateral deal and cannot be removed by the president of one country," Rouhani said in the live broadcast of the state TV, following Trump's aggressive remarks on Iran, Xinhua reported.

"Trump's remarks showed that the Joint Comprehensive Plan of Action (JCPOA) is stronger than what he treated during his presidential campaign," Rouhani said, adding that the US President failed to ally other parties involved in the clinch of deal with his policy over the nuclear deal.