Iran's Foreign Minister Mohammad Javad Zarif
Iran's Foreign Minister Mohammad Javad ZarifReuters

Iran warned on Sunday of “unpleasant” responses to new U.S. sanctions against it, Reuters reports.

The declaration by Iran’s Foreign Minister, Mohammad Javad Zarif, came after an announcement on Friday that Washington was going to penalize a number of Iranian and other foreign companies, banks and airlines for violating sanctions against Tehran, most of which are tied to a decade-old dispute about its nuclear program.

Washington said the moves were a signal that there would be no let-up of sanctions while international talks were underway to ease the economic measures in exchange for Iran's agreement to curb its nuclear activities.

On Sunday, Zarif told a news conference that Iran would respond to the sanctions "if deemed necessary," according to state news agency IRNA.

"We can take actions that would be unpleasant to the other side," he was quoted by Reuters as having said, without elaborating on what the measures might be.

Zarif added that the sanctions had been implemented to appease "pressure groups in the U.S. that are against any nuclear deal", using a phrase Iranian officials normally invoke to refer to Israeli interest groups.

On Saturday, noted Reuters, President Hassan Rouhani said the new curbs were unconstructive and against the spirit of the talks, although he added he was not pessimistic.

The latest sanctions come as Iran and Western powers continue talks on a permanent nuclear deal, as a follow-up to an interim deal that was reached in November.

The interim deal was set to expire on July 20, but the sides recently committed to a four-month negotiating extension through November 24, after they were unable to reach a permanent deal by the original deadline.

Iran seems to have toughened its positions in negotiations with the West. Iranian Supreme Leader, Ayatollah Ali Khamenei, recently said Iran "needs" 19 times more nuclear centrifuges than the amount being offered by world powers.

Iranian nuclear agency head Ali Akbar Salehi echoed Khamenei’s remarks a day later, saying Iran wants to greatly expand its uranium enrichment program despite Western fears that it could be used to make atomic arms.

Iran has previously insisted that it will never give up on what it sees as its right to uranium enrichment.