The Victorious is a US Navy ocean surveillance ship
The Pentagon has accused Chinese fishing boats of "dangerous" manoeuvres near a US Navy surveillance ship in the Yellow Sea last week.
Two boats came within 30 yards (27 metres) of the USNS Victorious in an "unsafe and dangerous" fashion on Friday, a statement said.
Correspondents say the US response was muted compared to its reaction to similar incidents earlier in the year.
Beijing accuses US vessels of entering its exclusive economic zone illegally.
There was no immediate Chinese response to the US statement on Tuesday.
Pentagon spokesman Bryan Whitman said the Victorious had been conducting "routine operations".
The Victorious sounded its alarm and shot water from its fire hoses to try to deter the vessels in an hour-long incident, one unnamed US official told the Associated Press news agency.
But the vessels did not leave until the Victorious radioed a nearby Chinese military vessel for help, Mr Whitman added.
Asked why the tone of the US statement was muted this time, he said: "We will be developing a way forward to deal with this diplomatically."
There have been four incidents in the past month in which Chinese-flagged fishing vessels manoeuvred too close to two unarmed ships staffed by civilians and used by the Pentagon for underwater surveillance and submarine-hunting missions, AP reported.