Iranian MPs have voted to classify the US armed forces and the CIA as terrorist groups.
A statement signed by 215 Iranian MPs cited the bombing of Japan during World War II, and the invasions of Vietnam and Iraq, as "terrorist actions".
The largely symbolic move comes days after the US Senate urged the White House to brand Iran's Revolutionary Guards as a terrorist organisation.
The foreign ministry in Tehran said it backed the MPs' motion.
Correspondents say the ministry's support is significant because government bodies are generally not as hardline as the parliament.
While the Iranian motion is seen as largely symbolic, the labelling of a group as a terrorist organisation by the US could have financial implications for the guards.
Any assets within US jurisdiction would be frozen and the US Treasury Department could move against firms subject to US law that do business with the guards.
The Revolutionary Guards force was established after the Islamic revolution toppled the Shah and brought hard-line clerics to power in Iran in 1979.It is estimated to have 125,000 active members and operates separately from Iran's main armed forces.