BEIRUT (Reuters) - Iran’s utmost authority Supreme Leader Ayatollah Ali Khamenei said the Islamic Republic had nothing to be concerned about, a report on his official website said on Wednesday, as the country’s clerical leadership faces biting U.S. sanctions.

FILE PHOTO: Iran's national flags are seen on a square in Tehran February 10, 2012, a day before the anniversary of the Islamic Revolution. REUTERS/Morteza Nikoubazl/File Photo

The sanctions imposed on Tehran this week have already led banks and many companies around the world to scale back dealings with Iran. Companies doing business with Iran will be barred from the United States, President Donald Trump said on Tuesday.

“With regard to our situation do not be worried at all. Nobody can do anything,” his website Khamenei.ir quoted him as saying in one of his speeches in the past weeks, but was published only a day after the new U.S. sanctions took effect.

Trump tweeted on Tuesday that the new sanctions, which were lifted under a 2015 international nuclear deal, were the most biting sanctions ever imposed.

Iran has denounced as “U.S. unilateralism” the reimposition of sanctions in line with Trump’s decision to pull out of the agreement over Iran’s nuclear program.

Iran’s ambassador to the United Nations Gholamali Khoshrou, in a commentary published by Britain’s Guardian newspaper on Wednesday, said that Trump was making history by violating a U.N. Security Council resolution it voted for three years ago.

The resolution, which underpinned the pact between Iran and six powers, calls on U.N. member states to refrain “from actions that undermine implementation of commitments” under the nuclear accord.

U.S. officials have said in recent weeks that they aim to pressure countries to stop buying oil from Iran in a bid to force Tehran to halt its nuclear and missile programs and involvement in regional conflicts in Syria and Iraq.

Iranian Foreign Minister Mohammad Javad Zarif said on Wednesday that a U.S. plan to reduce Iran’s oil exports to zero will not succeed, according to the Iran state newspaper.

“If the Americans want to keep this simplistic and impossible idea in their minds they should also know its consequences,” Zarif told the Iran newspaper.

“They can’t think that Iran won’t export oil and others will export.”

President Hassan Rouhani hinted last month that Iran could block the Strait of Hormuz, a major oil shipping route, if the United States attempted to stop the Islamic Republic’s oil exports.

Trump responded by noting that Iran could face serious consequences if it threatened the United States.

“The Americans have assembled a war room against Iran,” Zarif said. “We can’t get drawn into a confrontation with America by falling into this war room trap and playing on a battlefield.”

Last month, Trump offered to meet Iran’s leaders “without preconditions”. But Rouhani on Monday said there could be no talks as long as Washington was reneging on the deal.

Zarif said that Oman and Switzerland have acted as mediators in talks with America in the past but that there are currently no direct or indirect talks being held with the United States.

Rouhani, speaking in a meeting with North Korea’s foreign minister on Wednesday, said that America cannot be trusted, according to the State news agency IRNA.

“Today, America is identified as an unreliable and untrustworthy country in the world which does not adhere to any of its obligations,” Rouhani said.