At least one person was killed and 14 injured in an explosion in the southern Iranian port of Bandar Abbas on Saturday, a local official told Iranian news agencies, but the cause of the blast was not known.
The semi-official Tasnim news agency said that social media reports alleging that a Revolutionary Guard navy commander had been targeted in the explosion were "completely false".
Iranian media said the blast was under investigation but provided no further information. Iranian authorities could not immediately be contacted for comment.
Separately, four people were killed after a gas explosion in the city of Ahvaz near the Iraqi border, according to state-run Tehran Times. No further information was immediately available.
Two Israeli officials told Reuters that Israel was not involved in Saturday's blasts, which come amid heightened tensions between Tehran and Washington over Iran's crackdown on nationwide protests and over the country's nuclear program.
US 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.
Bandar Abbas, home to Iran's most important container port, 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 port suffered a major explosion last April that killed dozens and injured over 1,000 people. An investigative committee at the time blamed the blast on shortcomings in adherence to principles of civil defense and security.