The United States must keep its warships out of Iranian territorial waters in the Gulf or risk confrontation, the defence minister warned Thursday.
Every US ship that entered Iranian waters would first be warned, Hossein Dehghan was quoted by Tasnim news agency as saying, but if the intrusion was considered an invasion, there would be a confrontation, he said.
The warning follows an incident on Wednesday when a US warship and Iranian ships faced off near the Strait of Hormuz in the Gulf.
The US side claims its ship was in international waters, while Iran says it was in Iranian waters and therefore violated its territorial integrity.
A similar incident in January resulted in the arrest of 10 US marines, but they were quickly freed following urgent diplomatic negotiations between Iranian Foreign Minister Mohammad Javad Zarif and his US counterpart John Kerry.
Washington and Tehran have not had formal diplomatic ties for over 35 years, but Kerry and Zarif have been in regular contact since 2013 when the international community started hammering out a nuclear deal with Iran.