Iranian media reported that a blast struck the southern port of Bandar Abbas on Saturday, but did not provide any explanation for what caused it.

The semi-official Tasnim news agency said that social media reports alleging that a Revolutionary Guard navy commander was targeted in the explosion were "completely false".

The port of Bandar Abbas lies on the Strait of Hormuz, a vital waterway between Iran and Oman which handles about a fifth of the world's seaborne oil, The Caspian Post reports, citing Reuters.

The reported explosion comes amid heightened tensions between Tehran and Washington after Iranian authorities quelled the biggest protests to convulse the country in three years, and also amid ongoing Western concerns over Iran's nuclear programme.

The nationwide protests erupted in December over economic hardship and posed one of the toughest challenges to the country's clerical rulers.

At least 5,000 people were killed in the protests, including 500 members of the security forces, an Iranian official told Reuters. U.S. President Donald Trump said on Thursday an "armada" was heading toward Iran.

Multiple sources said on Friday that Trump was weighing options against Iran that include targeted strikes on security forces.

Earlier on Saturday, Iranian President Masoud Pezeshkian accused U.S., Israeli and European leaders of exploiting Iran's economic problems, inciting unrest and providing people with the means to "tear the nation apart”.