The order would also disrupt operations by foreign businesses that "provide support, services or assistance to, or otherwise associate with, terrorists," the Post said, citing unnamed US officials.
The Revolutionary Guard would be the first national military branch included on the US list of individuals, businesses, charities and groups believed to be engaged in terrorist activities.
The list includes al-Qaeda; Hezbollah, the Lebanese Shia movement; and Hamas and Islamic Jihad, both Palestinian groups. Estimates of the Revolutinary Guard's troop strength range from 125,000 to 350,000 soldiers.
Condoleezza Rice, US secretary of state, is reported to have informed her European counterparts of the plan.
The New York Times said that the Bush administration is unhappy with delays in securing approval from the UN Security Council for more economic sanctions against Tehran, citing US and European officials.
The order is contingent on Security Council moves to widen sanctions on Iran over its disputed nuclear programme, the newspaper said.
The US alleges that Iran is enriching uranium to create nuclear weapons.
Tehran has consistently denied the charge, saying it is only pursuing nuclear enrichment for civilian power generation.