Pentagon Spokesman Captain Jeff Davis said on Tuesday that the Iranian vessel had sailed directly in front of the USS Firebolt.
Carrying the story, Reuters said the US ship tried to communicate with the Iranian ship by radio three times but received no response.
A US military official, speaking on condition of anonymity, also claimed the interaction was unsafe, according to the report.
In a similar development on August 25, Pentagon officials said Iranian speedboats had harassed US warships in the Strait of Hormuz.
They said Iranian boats sped close to two US Navy destroyers with their weapons uncovered in the Strait of Hormuz in an unsafe and unprofessional encounter.
A day later, Irans Defense Minister Brigadier General Hossein Dehqan vowed that the Islamic Republic would confront any vessel intruding into its territorial waters.
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Irans Defense Minister Brigadier General Hossein Dehqan[/caption]If any foreign vessel enters our waters, we will give them a warning and if it is an act of aggression, we will confront them, said Dehqan, adding that Irans naval units monitorall movements in the Persian Gulf.
In January, Iran's Navy arrested the crews of two US patrol boats that had trespassed into Iranian territorial waters. Iran released them after deciding they had done so by mistake.
Iran has invariably asserted that it only uses its naval might for defensive purposes and to send across the Islamic Republics message of peace and security to other nations.
By Press TV
