"Increase your capabilities and readiness as much as you can so that the enemies of Iran will not dare threaten this great nation," Khamenei said in a meeting with Iran's naval chiefs, quoted on his official website.

The Islamic republic was confronted by "a vast lineup of enemies and rivals", he said.

Khamenei, quoted in English on his Twitter account, stressed that Iran "has no intention of launching a war against anyone".

But the country "should increase our aptitudes so that enemies will fear attacking Iran and threats against Iranian nation will perish".

He welcomed the commissioning this week of a destroyer and two submarines, all three manufactured in Iran, as signs of "ever increasing progress".

Defence Minister Amir Hatami, quoted by the official news agency IRNA, said two Ghadir-class submarines are to enter service on Thursday and a new destroyer two days later.

Iran considers itself the historic guardian of the Gulf and regularly condemns the US deployment of naval and air forces in the strategic waterway.