In a statement, foreign ministry spokesman Esmaeil Baqaei said the US policy of imposing sanctions on the Iranian people was a "clear contradiction with the United States' demand for dialogue and negotiation and indicates America's lack of goodwill and seriousness in this regard."

On Tuesday, the US Treasury imposed sanctions on Iranian liquefied petroleum gas magnate Seyed Asadoollah Emamjomeh and his corporate network.

It said in a statement the network was "collectively responsible for shipping hundreds of millions of dollars' worth of Iranian LPG and crude oil to foreign markets".

"Emamjomeh and his network sought to export thousands of shipments of LPG -- including from the United States -- to evade US sanctions and generate revenue for Iran," said Treasury Secretary Scott Bessent.

"The United States remains committed to holding accountable those who seek to provide the Iranian regime with the funding it needs to further its destabilising activities in the region and around the world."

The sanctions came as Tehran and Washington held two rounds of indirect nuclear talks in Muscat and Rome since April 12.

Since his return to office in January, US President Donald Trump has reimposed sweeping sanctions under his policy of "maximum pressure" against Tehran.

In March, he sent a letter to Iran's supreme leader Ayatollah Ali Khamenei calling for talks but warning of possible military action if they failed to produce a deal.

Oman said the third round, set for next Saturday, April 26, would again be held in Muscat.

On Tuesday, Iran announced that a technical, expert-level nuclear meeting between the two countries will also be held on Saturday, coinciding with the talks.

Following last Saturday's talks in Rome, Araghchi said the meeting was "good" and that the negotiations were "moving forward".

On Monday, Trump said Washington had "very good meetings" on Iran.

Western countries including the United States have long accused Iran of seeking to acquire nuclear weapons -- an allegation Tehran has consistently denied, insisting that its programme is for peaceful civilian purposes.