Any US move against a nuclear deal with Iran be an insult to the United Nations, Tehran's parliamentary speaker said.
Ali Larijani was speaking on a visit to Russia today hours before President Donald Trump delivers a speech expected to contain harsh criticism of the 2015 accord and Iran's activities that troubled Washington and its allies.
The agreement offered Iran relief from crippling economic sanctions in exchange for strict limits on its nuclear programme.
It involved a coalition of powers including the US, Britain, France, Germany, Russia and China.
Mr Larijani said the accord has received a UN blessing, so any move to spike it would represent an "insult to the UN".
He added that any revision of the deal would allow Iran to take its own action.