The government's strong defense of the IRGC's record comes as this week U.S. President Donald Trump is expected to decertify Iran's compliance with the nuclear deal and possibly designate the IRGC a terrorist organization as part of his new Iran strategy.
It came a day after the government said Washington itself would be aiding terrorism if it took such an action.
Iran has vowed to take "reciprocal measures" against the USA should its army, the Revolutionary Guards, be branded a terrorist organisation.
"We have all options on the table".
Chief of the Revolutionary Guards Mohammad Ali Jafari has also vowed to equate USA forces with the terrorist group Daesh (ISIS).
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The US has a complicated relationship with Iran's Revolutionary Guards, which is accused of supporting groups like Hamas and Hezbollah while also helping the US fight the Islamic State in Iraq and Afghanistan, the Atlantic reports.
Ali Akbar Velayati, the top adviser to Leader of the Islamic Revolution Ayatollah Ali Khamenei, said on Tuesday that "the Americans are too small to be able to harm the Revolutionary Guards".
His comments come just 24 hours after Iran threatened the USA with a "firm, decisive and crushing" response to sanctions. He must decide by Sunday whether to recertify the agreement, but is widely expected to declare Iran non-compliant with it, which would require Congress to make a decision on re-imposing sanctions.
Baker's warning echoed a similar one by Foreign Ministry spokesman Bahram Qasemi, who warned earlier on Monday warned that the country's reaction to the possibility of the Iran Revolutionary Guards being designated as a terror group would be "firm and crushing".