Tehran is firing rhetorical warning shots at the United States as President Trump prepares to announce what is expected to be a tougher policy toward Iran, including possibly declining to 're-certify' the 2015 nuclear deal and designating the Islamic Revolutionary Guard Corps as a terrorist organization.

In the runup to the decision, Iranian officials have threatened consequences if Trump targets the Islamic Revolutionary Guard Corps, or IRGC.

“I hope that the U.S. ruling body would not make the strategic mistake ... but if it does so, then Iran’s response will be firm, decisive, and crushing and the U.S. should accept its consequences,” Foreign Ministry spokesman Bahram Qasemi was quoted saying Monday by the Tasnim News Agency.

“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,” IRGC commander Mohammad Ali Jafari said Sunday, according to Reuters.

Ali Akbar Velayati, the adviser to Iran’s Supreme Leader Ayatollah Ali Khamenei, said if the U.S. labeled the IRGC a terrorist organization, then “all options were on the table,” Iranian news agency ISNA reported Monday.

“The Americans are too small to be able to harm the Revolutionary Guards,” Velayati said. “We have all options on the table. Whatever they do, we will take reciprocal measures."

IRANIAN ARMED FORCES SPOKESPERSON: 'IT'S TIME TO TEACH AMERICANS NEW LESSONS'

The president is expected to reveal his Iran policy plans this week, though no date has been set.

Two sources tell Fox News that the plan at the moment is for the president to announce he will not “re-certify” the Iran nuclear deal -- a decision he is expected to make every 90 days. This would trigger a congressional process to determine whether the United States should stay in the deal or seek changes, the sources said.

The president also is expected to call for a broader-approach strategy to confront Iran, including tougher measures against the regime.

On Tuesday, the head of Iran's nuclear agency argued Washington's international standing would suffer if the United States undermined the deal.

"The failure of the nuclear deal will undermine the political credibility and international stature of the U.S. in this tumultuous political environment," Iranian nuclear chief Ali Akbar Salehi said.

He expressed hope that "common sense shall prevail."

The U.S. administration has faced two 90-day certification deadlines so far to state whether Iran is meeting the conditions needed to continue enjoying sanctions relief under the deal. Each time, the U.S. has certified the deal.

But Trump more recently has said he does not expect to certify Iran's compliance with an Oct. 15 deadline looming.

Fox News’ John Roberts and Alex Pappas and The Associated Press contributed to this report.