Iran's President Hassan Rouhani on Wednesday blamed his US counterpart Donald Trump for the failure of French efforts to initiate a historic phone call between them last week at the United Nations.

The Islamic republic is prepared "to hold fruitful negotiations", he told the Iranian cabinet, referring to two days of diplomatic efforts by French President Emmanuel Macron.

"From my point of view, the path (to dialogue) remains clear,", he said in a speech carried on state television, thanking the French leader.

France's efforts at the UN General Assembly in New York "could have been acceptable, in a certain way", he said. "If anyone tried to prevent (contact taking place), it was the White House and nobody else".

While diplomatic efforts were in full swing, "the American president on two occasions" in the space of 24 hours "clearly announced an intensification of sanctions against Iran", said Rouhani.

"I said to our European friends: it's good but who should we believe? Should we believe what you are saying, that America is ready (to lift sanctions), or what the US president is saying?"

US President Donald Trump has suggested meeting Iranian leader Hassan Rouhani at a UN assembly in New York
US President Donald Trump has suggested meeting Iranian leader Hassan Rouhani at a UN assembly in New York AFP / Nicholas Kamm, HO

Trump phoned Rouhani on the sidelines of the UN summit but he refused to take the call, a French diplomatic source said Tuesday.

The call on September 24, the source said, came after Macron had shuttled between the US and Iranian leaders in a bid to arrange a historic encounter that he hoped would reduce the risk of all-out war in the Middle East.

"In New York, up to the last moment, Emmanuel Macron tried to broker contact, as his talks with presidents Trump and Rouhani led him to think contact was possible," the diplomatic source said.

The source said Macron made a last-ditch attempt before flying back to Paris, with French technicians installing a secure phone line linking Trump's Lotte hotel and the Millennium, hosting the Iranian delegation.

Macron went to the Millennium to ensure the phone call took place. Trump made the call, but Rouhani informed the French president he would not take it, the source said.

Speculation was abuzz last month that the leaders could meet on the sidelines of the General Assembly. But Rouhani stressed he would only hold talks with the US if Trump lifted economic sanctions on Iran.

Tensions between Tehran and Washington, which severed diplomatic ties in the aftermath of the 1979 revolution, have been escalating since May 2018 when Trump pulled out of a landmark nuclear accord and began reimposing sanctions that have crippled the Iranian economy.