The pledge came a week before President Donald Trump announces final decision on how he wants to contain Tehran. He is expected on Oct 15 to decertify a landmark 2015 international deal to curb Iran’s nuclear program, in a step that potentially could cause the accord to unravel.
“We are hopeful that the United States does not make this strategic mistake,” foreign ministry spokesman Bahram Qasemi was quoted as saying by the state news agency IRNA at a news conference.
“If they do, Iran’s reaction would be firm, decisive and crushing and the United States should bear all its consequences,” he added.
Individuals and entities associated with the IRGC are already on the US list of foreign terrorist organizations, but the organization as a whole is not.
IRGC commander Mohammad Ali Jafari said on Sunday “if the news is correct about the stupidity of the American government in considering the Revolutionary Guards a terrorist group, then the Revolutionary Guards will consider the American army to be like Islamic State all around the world.”
Jafari also said that additional sanctions would end the chances for future dialogue with the United States and that the Americans would have to move their regional bases outside the 2,000 km (1,250 mile) range of IRGC’s missiles.
The foreign ministry spokesman Qasemi also denied US accusations that Iran had cooperated with North Korea.
In an interview that was aired on Saturday night, Trump accused Iran of “funding North Korea” and “doing things with North Korea that are totally inappropriate”.
“Israel and some specific countries are raising these accusations to create Iranophobia.”
In his first speech to the UN General Assembly in September Trump called Iran “a corrupt dictatorship”, and the nuclear deal negotiated by his predecessor Barack Obama “an embarrassment”.
The deal, which was also supported by Britain, France, Germany, Russia and China, saw Iran agree to curbs on its nuclear program in return for the lifting of international sanctions that had damaged its economy.
Washington still maintains its own more limited sanctions on Iran over its missile program and over accusations it supports terrorism.