Airport spokeswoman Jenny Schiavone says United Airlines flight 867 landed safely Wednesday, and there were no injuries.
United Airlines spokesman Rahsaan Johnson says the captain diverted the flight to Denver after noticing an engine vibration that was out of the ordinary.
The captain decided to divert the 120-seat, twin-engine Airbus 319 to Denver so the plane could be checked.
The flight landed safely at Denver International Airport, and passengers were put on another plane. They arrived in San Francisco without incident at 11:30 a.m. PDT, about two hours later than originally scheduled.
Johnson didn't know if passengers had been aware of the engine issue while the plane was being diverted.