Iran warned the United States against designating its Revolutionary Guards Corp as a terrorist group and said USA regional military bases would be at risk if further sanctions were passed, state media reported on Sunday.
"The Guards are the defender of the nation", government spokesman Mohammad Bagher Nobakht told reporters.
An early shot across the bow came earlier in the day when USA authorities offered multimillion-dollar rewards for two officials of the Lebanese resistance group Hezbollah, a longtime Iran ally and fraternal partner founded shortly after the 1979 Islamic Revolution in Iran.
Ali Akbar Velayati, a top Iranian offical, appeared to suggest military options were being considered. But Iran's foreign ministry spokesman Bahram Ghasemi threatened a "firm, decisive and crushing" response if it went ahead.
The IRGC commander pointed out that diplomatic discourse is distinct from the discourse of defense forces, but their contents and orientations are the same.
His comments come as the Trump administration weighs whether to designate the Corps as a terrorist group.
He added that the United States approaches have frustrated people across the world, saying, "It is time to teach the United States new lessons".More news: Preckwinkle's sweetened beverage tax repealed
"If American officials make such a strategic mistake, the Islamic Republic of Iran will take a reciprocal measure", Zarif said on Monday, adding, "Some measures have been thought out in this regard and will be taken at the appropriate time".
Trump, who has called the landmark 2015 accord agreed between Iran and six world powers the "stupidest" and "one of the worst and most one-sided transactions the United States has ever entered into" in history, is expected to announce that he will decertify the deal ahead of an October 15 deadline, a senior administration official said last week.
Trump's announcement would stop short of pulling out of the agreement but give Congress 60 days to decide whether to reimpose sanctions.
All the other signatories to the agreement - Britain, France, Germany, China and Russian Federation - have urged the United States to stick with the deal, saying Iran has so far stuck to its commitments to restrict its nuclear programme.
"It seems the Trump administration understands nothing but expletives and needs some shocks to learn the new concept of power in today's world", Deputy Chief of Staff of Iran's Armed Forces Brigadier General Massoud Jazayeri said on Tuesday.
President Hassan Rouhani of Iran on Wednesday warned that the United States would be the loser if President Donald Trump decides to drop Iran's global nuclear deal. "It is time to teach them a new lesson".