Iran's Supreme Leader has warned Iran would react strongly to any "wrong move" by the United States on Tehran's nuclear accord with world powers.

Ayatollah Ali Khamenei's statement comes days after Donald Trump said Iran had violated the agreement's "spirit".

"The Iranian nation is standing firm and any wrong move by the domineering regime regarding the [nuclear accord] will face the reaction of the Islamic Republic," state television quoted the Ayatollah as saying.

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The US President had called the nuclear accord "one of the worst deals I've ever seen" and hinted he may attempt to rescind the deal.

"You'll see what I'm going to be doing very shortly in October," Mr Trump said. "The Iran deal is one of the worst deals I've ever seen.

"Certainly at a minimum the spirit of the deal is atrociously kept. The Iran deal is not a fair deal to this country. It's a deal that should not have ever been made."

Washington extended some sanctions relief for Iran on Thursday under Tehran's 2015 deal with world powers but said it had yet to decide whether to maintain the agreement.

"Today, despite all the commitments and discussions in the negotiations, America's attitude towards these negotiations and their outcome is completely unjust and amounts to bullying," Mr Khamenei said.

"The Americans should know that the Iranian people will stand firm on their honourable positions and on important issues related to national interests, there will be no retreat by the Islamic Republic," he added in a speech to Iranian military academy graduates.

Iran's 'Trumpism' contest Show all 10 1 /10 Iran's 'Trumpism' contest Iran's 'Trumpism' contest A picture taken on July 3, 2017 shows a cartoon of US President Donald J. Trump and First Lady Melania Trump on display at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest An Iranian woman looks at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest An Iranian woman looks at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest Iranian cartoonist Hadi Asadi poses for a picture with a trophy and an award next to cartoons of US President Donald J. Trump, at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest Iranians look at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest An Iranian woman looks at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest Iranian reformist cleric Mahmoud Doaei looks at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest An Iranian man looks at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest An Iranian woman looks at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images Iran's 'Trumpism' contest Iranian reformist cleric Mahmoud Doaei looks at cartoons of US President Donald J. Trump at an exhibition of the Islamic Republic's 2017 International Trumpism cartoon and caricature contest, in the capital Tehran on July 3, 2017. / AFP PHOTO / ATTA KENARE (Photo credit should read ATTA KENARE/AFP/Getty Images) AFP/Getty Images

Iran said last month it could abandon the nuclear agreement "within hours" if the US imposes any new penalties, after Washington ordered sanctions over Tehran's ballistic missile tests.

The US imposed unilateral sanctions after saying the missile tests violated a UN resolution, which endorsed the nuclear deal and called upon Tehran not to undertake activities related to ballistic missiles capable of delivering nuclear weapons, including launches using such technology. It stopped short of explicitly barring such activity.

Iran denies its missile development breaches the resolution, saying its missiles are not designed to carry nuclear weapons.

The head of Iran's atomic programme previously warned the country would be able to create highly enriched uranium within five days of the US ending the nuclear agreement.

Ali Akbar Salehi, one of Iran’s vice presidents, made the comments on state TV in apparent reaction to increased sanctions imposed by America last month.

He suggested the country could achieve 20-per cent enriched uranium in "at most" five days - a level at which it could then be processed further into weapons-grade nuclear material.