TEHRAN, Aug. 1 (Xinhua) -- Iranian authorities on Thursday unanimously condemned the U.S. sanctions on Iran's Foreign Minister Mohammad Javad Zarif, while expressing support for the Iranian top diplomat.

Iranian President Hassan Rouhani denounced the U.S blacklisting of Zarif as a sign of "frustration", saying that "Zarif's logical remarks rattle the White House," according to Tasnim news agency.

Rouhani lashed out at the U.S. government for "the paradoxical policy" of expressing readiness for talks with Iran and at the same time imposing sanctions on its top diplomat.

The U.S. move to blacklist Zarif reveals that "our enemies are so frustrated that they have even lost the opportunity for exercising intellect and wisdom," he made the remarks during a Thursday trip to the northwestern city of Tabriz in the province of East Azarbaijan.

By sanctioning the Iranian foreign minister, the Americans "are resorting to childish behaviour," Rouhani said.

The U.S. on Wednesday announced that it has sanctioned Zarif, amid high tensions between the two sides.

The U.S. Treasury Department alleged that Zarif "acted or purported to act for or on behalf of, directly or indirectly, the Supreme Leader of the Islamic Republic of Iran," who was already sanctioned by the U.S. in June.

Zarif quickly responded to the U.S. action on social media, quipping that he was grateful to be considered a "huge threat."

"It has no effect on me or my family, as I have no property or interests outside of Iran," Zarif said in a tweet, "Thank you for considering me such a huge threat to your agenda."

On Thursday, Iranian Foreign Ministry spokesman Abbas Mousavi said that "the Americans are seriously scared by the logic of Zarif and his art of negotiations."

"The Americans are intensely afraid of Dr. Zarif's logic and his negotiation skills," Mousavi said.

In a statement released on Thursday, the General Staff of the Iranian Armed Forces said Washington's "illegal" move to designate Zarif reflects its "weakness and humiliation."

"The undiplomatic measure to sanction Iran's foreign minister reflects Washington's frustration and is seen as an attempt to make up for the U.S. successive defeats in the world and region," the statement said.

Also, Iran's Islamic Revolution Guards Corps (IRGC) on Thursday denounced the U.S. sanctions on Zarif, as a move in line with the U.S. policy of exerting maximum pressure on the Islamic republic.

By sanctioning Zarif, the Americans "once again demonstrated their anger at the spread of the Islamic Revolution's inspiring and anti-arrogance discourse, and unveiled their mischief and animosity toward the dignified Iranian establishment and nation," the IRGC said.

The U.S.-Iran ties have deteriorated significantly after Washington walked away from the landmark 2015 Iran nuclear deal in May 2018 and reimposed energy and financial sanctions, which had been removed under the deal, on Iran.

In response, Iran has also suspended parts of its commitments to the nuclear deal and threatened to go further.