Iran would find it "really easy" to close the world's most important oil transit channel, the Strait of Hormuz at the Gulf's entrance, but would not do so right now, Iran's navy chief said on Wednesday.
"Shutting the strait for Iran's armed forces is really easy -- or as we say (in Iran) easier than drinking a glass of water," Admiral Habibollah Sayari said in an interview with Iran's Press TV.
"But today, we don't need (to shut) the strait because we have the Sea of Oman under control, and can control the transit," he said.
The United States warned Iran against any attempt to disrupt shipping.
"Interference with the transit... of vessels through the Strait of Hormuz will not be tolerated," said Pentagon press secretary George Little.
Sayari was speaking a day after Vice President Mohammad Reza Rahimi threatened to close the strait if the West imposed more sanctions on Iran, and as its navy held war games in international waters to the east of the channel.
World prices briefly climbed after Rahimi warned on Tuesday that "not a drop of oil will pass through the Strait of Hormuz" if the West broadened sanctions against Iran over its nuclear programme.
"The enemies will only drop their plots when we put them back in their place," the official news agency IRNA quoted Rahimi as saying.
More than a third of the world's tanker-borne oil passes through the Strait of Hormuz, a strategic choke point that links the Gulf -- and its petroleum-exporting states of Bahrain, Iran, Kuwait, Qatar, Saudi Arabia and the United Arab Emirates -- to the Indian Ocean.
The United States maintains a naval presence in the Gulf in large part to ensure that passage for oil remains free.
But Sayari asserted that the Strait of Hormuz "is completely under the control of the Islamic Republic of Iran."
He said Iran's navy was constituted with the aim of being able to close the strait if necessary.
"The Iranians conduct exercises on a fairly routine basis in this area. That's something that we know about," Little said in Washington.
"That being said, any effort to raise the temperature on tensions surrounding the Strait of Hormuz is unhelpful," he said, adding that there was no sign of Iran taking provocative steps near the channel.
"I'm unaware of any aggressive hostile action directed toward US vessels in the Persian Gulf or the Strait of Hormuz," or against other ships, Little said.
France called on Iran to respect international law and allow unhindered passage of all ships through the strait.
Sayari, meanwhile, said the navy manoeuvres east of the strait were designed to show Gulf neighbours the power of Iran's military over the zone.
Ships and aircraft dropped mines in the sea on Tuesday as part of the drill, and on Wednesday drones flew out over the Indian Ocean, according to a navy spokesman, Admiral Mahmoud Mousavi.
Iran has several times said it is ready to target the strait if it is attacked or economically strangled by Western sanctions over its nuclear programme.
An Iranian lawmaker's comments last week that the navy exercises would block the Strait of Hormuz briefly sent oil prices soaring before that was denied by the government.
Tehran in September rejected a Washington call for a military hotline between the capitals to defuse any "miscalculations" that could occur between their navies in the Gulf.
In Washington, US State Department deputy spokesman Mark Toner dismissed Rahimi's threat.
"I just think it's another attempt by them to distract attention from the real issue, which is their continued non-compliance with their international nuclear obligations," Toner told reporters.
The United States and other Western countries accuse Iran of using its uranium enrichment programme to build nuclear weapons. Iran denies the charges.
Extra US and European sanctions aimed at Iran's oil and financial sectors are being considered.
A European Union spokesman said on Wednesday the bloc was pressing ahead with those plans regardless of Tehran's threat.