Donald Trump's administration has not contacted the head of the United Nations' atomic agency or others about their criticism of the Iran nuclear deal, he said.
Yukiya Amano, the director-general of the International Atomic Energy Agency, said that his organisation was "in constant touch" with the US, but had yet to hear from the new administration on their concerns.
He said: "I'm expecting to have direct contact with the new administration very soon."
During his presidential campaign, Mr Trump said he wanted to renegotiate the Iran deal, without elaborating.
The accord limits Iran's ability to enrich uranium in exchange for the lifting of economic sanctions.
Mr Amano was in Dubai as part of the annual World Government Summit.
The deal, which is formally known as the Joint Comprehensive Plan of Action (JCPOA), was struck between the European Union, China, France, Germany, Russia, the UK, the US and Iran.
Under the agreement, Iran suspended and dismantled a large part of its nuclear program in exchange for the lifting of many — but not all — sanctions against the country.
Iran conducted another ballistic missile earlier this month prompting the Trump administration into imposing new economic sanctions against Iran.
Afterwards, the US President tweeted, "Iran, #1 in terror", and questioned how the 2015 agreement was ever signed.
