Iran's President Hassan Rouh on Thursday said that the United States's decision to impose sanctions on Foreign Minister Mohammad Javad Zarif implies that Washington is 'afraid' of the top diplomat.
"They are afraid of our foreign minister's interviews," Rouh said in a televised address.
"It is completely clear that the foundations of the White House have been shaken by the words and logic of an informed, devoted and diplomatic individual," he added.
On Wednesday, Washington imposed sanctions on Zarif for acting on behalf of Iran Supreme Leader Ayatollah Ali Khamenei, who is also subject to recently-imposed US sanctions.
"Zarif implements the reckless agenda of Iran's supreme leader (Ayatollah Ali Khamenei), and is the regime's primary spokesperson around the world," Treasury Secretary Steven Mnuchin said in a statement.
Iran's President Hassan Rouh termed the US' decision of imposing maximum pressure on Iran as "childish" that has come amid escalating tensions between the two countries.
He was quoted as saying that the US was "resorting to childish behaviour ... They were claiming ever day 'We want to talk, with no preconditions' ... and then they sanction the foreign minister."
"Our enemies are so helpless that they have lost the ability to act and think wisely," the president added.
The US, which last year unilaterally withdrew from a landmark nuclear deal signed between Iran and world powers in 2015, has previously proposed unconditional talks with Tehran - even as it reimposed punishing economic sanctions, including measures aimed at slashing Iran's oil exports to zero.
In addition, fears of a direct conflict between the two have risen since May, this year, following several incidences of attacks or seizure of oil tankers in the Gulf, as well as Iran's downing of a US surveillance drone.
On his part, Zarif brushed off the sanctions, which would further freeze any of his assets, on Twitter, saying that the US move indicated that Washington saw him as a "threat".
"It has no effect on me or my family, as I have no property or interests outside of Iran," he said.
Zarif visited the United Nations headquarters in New York last month, but his movement was restricted by the administration to a small area near the world body's headquarters.
( With inputs from ANI )