The Trump administration said Wednesday it has imposed financial sanctions on Iranian Foreign Minister Mohammad Javad Zarif, saying he carries out the country's "reckless agenda" and acts as an apologist for the regime.

The move, though largely symbolic, could complicate any attempt to open up direct talks between Washington and Tehran. The designation underscored the lack of any dialogue between the two countries, despite increasingly hostile rhetoric and a series of tense standoffs in the Persian Gulf that have raised the possibility of a potential war.

"The United States is sending a clear message to the Iranian regime that its recent behavior is completely unacceptable," Treasury Secretary Steven Mnuchin said in a statement. He called Zarif the chief spokesman for a government that he said blocks the flow of information to its own people.

"At the same time the Iranian regime denies Iranian citizens' access to social media, Foreign Minister Javad Zarif spreads the regime's propaganda and disinformation around the world through these mediums," Mnuchin said.

Iran and the United States have had no diplomatic relations for four decades but Zarif had been a key interlocutor for the previous administration in its diplomacy with Tehran.

Zarif, who speaks fluent English with an American accent and studied for years in the United States, forged a rapport with former secretary of state John Kerry during President Barack Obama's tenure, as part of negotiations that led to the 2015 nuclear deal.

But there is no rapport and no dialogue between Zarif and his current U.S. counterpart, Mike Pompeo. President Donald Trump last year withdrew the United States from the nuclear deal, which had introduced restrictions on Iran's nuclear program in return for the easing of U.S. and U.N. sanctions.

Since Washington pulled out of the accord, Trump has imposed tough economic sanctions that have drastically slashed Iran's oil exports and helped fuel inflation.

Republican Sen. Rand Paul of Tennessee, who Trump has authorized to seek out possible talks with Iran, criticized the sanctions on Zarif.

"I think if you sanction diplomats you get less diplomacy," he said. "It's a mistake to sanction diplomats, we will get less diplomacy."

Democratic Sen. Dianne Feinstein of California, who has spoken to Zarif often over more than a decade, said the designation of the foreign minister would only undermine the possibility for diplomacy.

“President Trump says he pulled out of the Iran nuclear agreement to force Iran back to the negotiating table, but this move limits the opportunity to do exactly that. This doesn’t move us closer to peace, it further escalates an already tense situation.”

But Sen. Lindsey Graham of South Carolina, who backs the administration’s tough line on Iran, praised the move. "I think the guy deserves it," Graham said. "He's empowering this regime that is the largest state sponsor of terrorism."

Senior administration officials said the sanctions on Zarif did not preclude any future dialogue with Iran, and they questioned whether the foreign minister had the standing in the regime to deliver on any negotiations.

"So I do not consider him to be our primary point of contact. In addition, I think if we do have an official contact with Iran, we would want to have contact with somebody who is a significant decision maker," one senior official, who spoke on condition of anonymity, told reporters.

In a statement, Secretary of State Pompeo said the administration was still committed to diplomacy: "The United States continues to seek a diplomatic solution that addresses the Iranian regime's destructive behavior. The only path forward is a comprehensive deal that addresses the full range of its threats."

Administration officials also indicated the sanctions would not prevent Zarif from representing Iran on official business at the United Nations headquarters in New York.

"The State Department will evaluate specific circumstances related to this designation on a case by case basis consistent with existing laws and obligations and this includes the United Nations headquarters agreement," the senior administration official said.

The designation of Zarif comes more than a month after the White House said it planned to take action against the Iranian foreign minister. The Trump Administration sanctioned the office of the country's supreme leader, Ayatollah Ali Khamenei, at the end of June, at which point Mnuchin told reporters Zarif would be sanctioned later that week.

Zarif immediately ridiculed the sanctions in a tweet. "The US' reason for designating me is that I am Iran's 'primary spokesperson around the world," the foreign minister wrote. "Is the truth really that painful? It has no effect on me or my family, as I have no property or interests outside of Iran. Thank you for considering me such a huge threat to your agenda."

Zarif, whose two children were born in the United States, had previously dismissed the prospect of sanctions as an empty gesture, telling the New York Times: "I personally do not even have a bank account outside Iran. Iran is my entire life and my sole commitment. So I have no personal problem with possible sanctions."

The move is the latest in a wave of sanctions that the Trump administration has introduced against Iran as part of its "maximum pressure" campaign, which it says is designed to force Iran to halt its support for militants in the Middle East, scale back its ballistic missile program and abandon nuclear activities.

Wednesday's announcement came amid frustration among Iran hawks in Congress over the administration's plans to renew waivers on Tehran that allow it to run a limited civilian nuclear program with assistance from countries that signed the 2015 nuclear accord.

The administration has been locked in an intense debate over how to proceed with the waivers, which are due to expire this week.

Treasury secretary Mnuchin and other administration officials appeared to prevail in the policy argument against national security adviser John Bolton and Secretary of State Mike Pompeo, sources familiar with the matter told NBC News.

The internal debate hinges on whether the United States would have more leverage in any future talks with Iran by totally dismantling the 2015 deal, or whether it is better to preserve the accord as a starting point for negotiations, U.S. officials say.