Iran must take steps to de-escalate its nuclear program if it wants to make room for diplomatic relations with the United States, starting with cooperation with the International Atomic Energy Agency (IAEA), the US State Department said.

"In the last few weeks, we have seen Iran take steps to undermine the IAEA's ability to do its job. So if Iran is really serious about taking de-escalation steps, the first thing it can do is cooperate with the IAEA," State Department spokesman Matt Miller said.

He added that the steps he outlined as a potential prelude to renewed U.S.-Iran talks were directly or indirectly related to Iran's nuclear program, though he did not provide further details.

The US and many of its Western allies fear that Iran's nuclear program could be a cover for developing nuclear weapons, which Iran denies.