"America is never going to be held hostage to the Iranian regime's nuclear blackmail," US envoy for Iran Brian Hook said.

The Iranian decision came on the anniversary of the US withdrawal from the agreement, which placed limits on the Islamic Republic's nuclear program.

And it coincides with rising tensions, with the US announcing deployments of a carrier strike group and several B-52 bombers to the Gulf region.

"We are committed to denying the Iranian regime all paths to a nuclear weapon," Hook said.

"We will continue to impose maximum pressure on the regime until it abandons its destabilizing ambitions and we very much want the international community to hold the regime accountable for its threat to expand its nuclear program."