"Iran is not currently talking with the US directly", Hossein Amir-Abdollahian said in televised remarks.

"But, if during the negotiation process we get to a point that reaching a good agreement with solid guarantees requires a level of talks with the US, we will not ignore that in our work schedule," he added.

The 2015 deal -- agreed by Iran, the US, China, Russia, Britain, France and Germany -- offered Tehran sanctions relief in exchange for curbs on its nuclear programme.

But the US unilaterally withdrew in 2018 under then-president Donald Trump and reimposed biting economic sanctions, prompting Tehran to begin rolling back its commitments.

Talks aimed at salvaging the deal started last year in Vienna between Iran and countries still part of the accord. The US has been taking part indirectly in negotiations.

Iran had previously stated that the US must "change course" and return to the nuclear deal, prior to any direct talks between the two arch-foes in Vienna.

"Our direct talks are with P4+1," said Amir-Abdollahian, referring to Germany and permanent Security Council powers France, China, Britain and Russia.

"And our indirect negotiations with the US currently are... via (EU diplomat Enrique) Mora and one or two other countries present at Vienna talks," he added.

"Meanwhile, the US side is sending messages in different ways that it seeks a level of direct talks with Iran," he added during a conference at the foreign ministry in Tehran.

The negotiations, which seek to bring Washington back to the accord and ensure Iran returns to its commitments under the deal, started in April, and resumed in late November, after they were suspended in June as Iran elected ultraconservative President Ebrahim Raisi.