Iranian media say the parliament has approved a bill that labels all US military forces as terrorist.
The legislation is a step further after Iranian lawmakers last week approved a bill labelling US troops in the Mideast as terrorist, a day after the US terrorism designation for Iran's Revolutionary Guard came into effect.
The report by the semi-official ISNA news agency says 173 out of 215 lawmakers at the session voted for the bill on Tuesday.
The bill also demands the Iranian government take unspecified action against other governments that formally back the US designation.
Saudi Arabia, Bahrain and Israel have all supported the Trump administration's designation.
The US on Monday said it will no longer exempt any countries from US sanctions if they continue to buy Iranian oil.