Iran said on Saturday that US military ships would never be allowed to enter the Gulf "under any circumstances" and that President Donald Trump would "take that dream to his grave".
The remarks came amid mounting US and Israeli threats of renewed attacks on Iran, as US ambassador to Turkey Tom Barrack warned that Washington could "absolutely" strike Iran as soon as this weakened.
"We will not allow US military ships in the Persian Gulf under any circumstances and at any time," said Iran's armed forces chief of staff Ali Abdollahi, according to Iranian state television.
"The US president must dream of seeing the armed forces enter the Persian Gulf. He will take that dream to his grave."
Iranian forces have restricted traffic through the Strait of Hormuz, a vital energy conduit and gateway to the Gulf, since the war with the United States broke out on 28 February.
In retaliation, the United States has imposed a counterblockade on Iranian ports and ships.
Tehran has required vessels to seek permission to transit, and repeatedly targeted ships attempting to pass through Hormuz via a southern route close to the Omani coast.
According to the Guards, several tankers attempting to transit Hormuz through the route Tehran considers "illegal" were hit by mines in recent days.
On Friday, the Guards said two supertankers carrying more than 4.5 million barrels of crude oil have been abandoned at sea after hitting mines in the strategic waterway.
"Their engine rooms were disabled by an explosion and a fierce fire," the Guards said in a statement carried by their Sepah News website.
In peacetime, around a fifth of the world's oil and gas passed through Hormuz.
US spy chief warns Iran has ramped up efforts to target Americans
Iran has "substantially increased" its efforts to target Americans in the Middle East and beyond, US national intelligence chief Jay Clayton warned on Friday.
The warning comes after Washington ordered non-essential US embassy staff and their families to leave Saudi Arabia this week, following increasing attacks from Yemen's Houthis.
The kingdom has come under near-daily attacks this month from the Iran-backed group, including a strike on Riyadh's international airport that was the kingdom's deadliest in years.
"We have received intelligence that Iran has substantially increased efforts to target US personnel," Clayton said in a memo sent to Secretary of State Marco Rubio, according to a US official.
"The lethal plotting efforts by the Iranians against US citizens have reached advanced stages in both the Middle East and certain other countries," said the memo, which was first reported by Axios.
Washington previously ordered non-essential staff to leave the Gulf ahead of the start of its war against Iran and again in July before Trump called off a new wave of strikes.
The US official said: "When it comes to our staffing at embassies, we constantly evaluate new information about the security environment."
"The threat of Houthi attacks and of Iranian terror plots targeting US officials are informing our decisions," the official added.
Trump suggested on Friday that the US might launch renewed military operations against Iran.
"We may do another little Epic Fury", Trump said, referring to the US name for its attacks on Iran. He gave no indication of timing.
