National security adviser John Bolton responds to a question from the news media during the daily briefing Thursday at the White House. (SHAWN THEW/EPA-EFE/Shutterstock)

The United States is “very serious” about applying pressure on Iran through the reinstatement of sanctions but is not seeking regime change, White House national security adviser John Bolton said Monday.

Bolton’s remarks come as the Trump administration prepares to reimpose the first round of trade sanctions against Iran following the U.S. withdrawal from the 2015 Iran nuclear deal in May.

“Our policy is not regime change, but we want to put unprecedented pressure on the government of Iran to change its behavior, and so far, they’ve shown no indication they’re prepared to do that,” Bolton said in an interview Monday on Fox News.

He described the Iranian regime as standing “on very shaky ground” and argued that protests in the country were due to dissatisfaction with Iran’s leaders and its collapsing economy rather than opposition to U.S. sanctions.

Beginning Tuesday morning, Iran will be prohibited from using U.S. dollars, trade in metals and sales of Iranian-made cars will be banned, and permits allowing the import of Iranian carpets and food will be revoked, among other steps aimed at pressuring Tehran to change its behavior and renegotiate the nuclear accord.

Last month, President Trump said he was willing to meet with Iran’s leaders “anytime they want” and without preconditions. Bolton reiterated that invitation on Monday and said that “if the ayatollahs want to get out from under the squeeze, they should come and sit down.”

“They should not underestimate our determination that we’re going to put pressure on them until they give up their pursuit of nuclear weapons and all the other activities that I mentioned,” Bolton said. “That, we are very serious about.”

Iran explicitly agreed not to pursue nuclear weapons in the 2015 agreement. U.S. intelligence agencies have concluded that Iran halted a nuclear weapons program in 2003 and did not have one at the time of the accord.

Congressional reaction on Monday to the restoration of sanctions split largely along party lines.

Republicans hailed the move as a much-needed step toward putting pressure on Iran to end its support for militants in the region, halt its ballistic missile program and agree to modify sunset provisions in the nuclear accord.

“Under these new sanctions businesses throughout the world will have to choose to do business with the American economy or Iranian economy? You can’t do both,” Sen. Lindsey O. Graham (R-S.C.), who went golfing with Trump over the weekend, said in a tweet.

“Make Iran Great Again,” he added, in a new twist on Trump’s campaign slogan. “Dump the Ayatollah!”

Rep. Marsha Blackburn (R-Tenn.), who last week won her state’s Republican Senate nomination, also voiced support for the sanctions, which she said “are needed to hold Iran accountable.”

“I fully support @realDonaldTrump’s reinstatement of sanctions against #Iran,” Blackburn said in a tweet. “The Obama #IranDeal emboldened the largest state sponsor of terrorism & put the security of our nation & allies at risk.”

Democrats, meanwhile, argued that the move would make the world more dangerous, not safer.

Sen. Richard J. Durbin (D-Ill.), who was instrumental in shepherding the original Iran deal through Congress three years ago, said in a statement that he remains opposed to the Trump administration’s “irrational hostility” to the agreement.

“Today’s actions, yet again, put the U.S. in violation of this deal. It risks reopening a resolved conflict, and will divide us further from our European allies. President Trump’s foreign policy is a dangerous gamble with nuclear weapons,” Durbin said.

Rep. Chellie Pingree (D-Maine), who sits on the House Armed Services Committee, said that Trump “should not have ripped up a functioning agreement.”

“This misguided decision again risks putting Iran back on the nuclear weapons development track and further distances us from our allies,” she said.

Carol Morello, Anne Gearan and William Branigin contributed to this report.