The US Department of Defence (DoD) confirmed, on Tuesday, that one of its navy vessels patrolling the Persian Gulf was forced into a rapid change of course when an Iranian craft approached it at high speed.
The near collision, which took place on Sunday, follows three similar incidents in the last month according to DoD officials.
An official, speaking to Reuters, said "We don't see this type of unsafe and unprofessional activity from any other nation."
Diplomatic tensions between the two states had eased somewhat, as a result of a high profile deal over Iran's nuclear programme last year. However, the US' close alliance with Iran's regional rivals and its massive military presence in the Persian Gulf are a constant sore in the side of the Islamic Republic.