(CNN) The United States sanctioned Iranian Foreign Minister Mohammad Javad Zarif Wednesday, following through on a weeks-old threat that is likely to elevate already heightened tensions with Iran.

Senior administration officials said that the designation was due to Zarif's actions on behalf of Iran's Supreme Leader Ayatollah Ali Khamenei, whom the administration sanctioned in late June.

"Today President (Donald) Trump decided enough is enough," a senior administration official said on a call with reporters.

In a statement, Treasury Secretary Steven Mnuchin said the outspoken Iranian foreign minister "implements the reckless agenda of Iran's Supreme Leader, and is the regime's primary spokesperson around the world."

"The United States is sending a clear message to the Iranian regime that its recent behavior is completely unacceptable," he said.

Under the designations, "all property and interests in property of this individual that are in the United States or in the possession or control of U.S. persons must be blocked and reported" to the Treasury's Office of Foreign Assets Control (OFAC), according to a Treasury release.

Zarif dismissed the sanctions in a message on Twitter, noting that he has "no property or interests outside of Iran."

"The US' reason for designating me is that I am Iran's 'primary spokesperson around the world' Is the truth really that painful?" he wrote Wednesday. "Thank you for considering me such a huge threat to your agenda."

In terms of the sanctions' impact on Zarif's potential travel, including to the forthcoming United Nations General Assembly, a senior administration official said, "The State Department will evaluate specific circumstances related to this designated on a case-by-case basis consistent with existing laws."

Those existing laws include the United Nations Headquarters Agreement, under which the US "will continue to uphold obligations," that official said.

CNN reported in mid-July that the US was holding off on sanctioning Zarif for the time being, despite Mnuchin telling reporters that Trump had directed him to impose sanctions on Zarif.

Wednesday's sanctions against Iran's top diplomat come as the administration has sought to straddle the line between its so-called "maximum pressure" campaign and its stated willingness to negotiate "without preconditions."

As recently as a month ago, Trump appeared open and eager for talks with Iran over its nuclear program. But Iranian officials offered little indication they were open for talks, discounting Trump's overtures. In recent days, Trump has sounded less optimistic for diplomacy and more hawkish in his approach to Iran, according to people who have spoken with him on the topic.

Asked who would be the point of contact for nuclear negotiations with Iran moving forward, an official said the US does "not consider him (Zarif) to be our primary point of contact."

If there are future negotiations, the US "(wants) to have contacts with somebody who is a significant decision maker," the official continued.

Zarif "was the point of contact for the previous administration's nuclear negotiations," that official said, adding, "As you might have noticed, we actually withdrew from the (Joint Comprehensive Plan of Action)."

Administration officials, including Secretary of State Mike Pompeo, have recently sought to play down Zarif's authority within Iran. Pompeo, who has frequently called out his Iranian counterpart, said in a statement that Wednesday's "action represents another step toward denying the Iranian regime the resources to enable terror and oppress the Iranian people."

The sanctions against Zarif are likely to be seen as another hurdle to European allies, who have been working to preserve the landmark 2015 nuclear deal amid escalatory actions by Iran. Earlier on Wednesday, Germany announced it would not participate in a US-led naval mission in the Strait of Hormuz.

"We consider the strategy of applying maximum pressure to be wrong," Foreign Minister Heiko Maas said.

On Sunday, representatives from France, Germany, the United Kingdom, the European Union, Russia, China and Iran met in Vienna to reaffirm their continued commitment to the Iran nuclear deal.