The head of the navy of Iran's Revolutionary Guards, General Alireza Tangsiri, says Iran has full control of the Gulf and the US Navy does not belong there.
Tehran has suggested it could take military action in the Gulf to block other countries' oil exports in retaliation for US sanctions intended to halt its sales of crude. Washington maintains a fleet in the Gulf that protects oil shipping routes.
Tangsiri was quoted by Tasnim news agency on Monday that Iran had full control of the Gulf and the Strait of Hormuz that leads into it. Closing the strait would be the most direct way of blocking shipping.
"We can ensure the security of the Persian Gulf and there is no need for the presence of aliens like the US and the countries whose home is not in here," he said in the quote, which appeared in English translation on Tasnim.
He added, "All the carriers and military and non-military ships will be controlled and there is full supervision over the Persian Gulf. Our presence in the region is physical and constant and night and day."
Separately, the head of the Revolutionary Guards, Major General Mohammad Ali Jafari, said Iran's enemies would not prevail in a conflict.
"The enemies are strictly avoiding any conflict with Iran because they know that it will not be beneficial for them," Jafari said, according to Tasnim.
Tension between Iran and the United States has escalated since President Donald Trump pulled out of a 2015 nuclear deal between Iran and world powers in May and reimposed sanctions.
Senior US officials have said they aim to reduce Iran's oil exports to zero.
Iran's Supreme Leader Ayatollah Ali Khamenei, the most senior authority in the Islamic Republic, said last month that he supports the idea that if Iran is not allowed to export oil then no country should export oil from the Gulf.
Reporting by Babak Dehghanpisheh; Editing by Dale Hudson and Peter Graff/Reuters.