The 30-year-old man was shot near the 2008 Suzuki motorcycle, parked in an alley on Blake Avenue, just after 2:30 a.m.
The sergeant believed the man was attempting to break the motorcycle's lock.
He confronted the man, who moved toward the off-duty officer.
The officer fired four times, and one of the bullets hit the man. He was taken to Brookdale Hospital in stable condition.
The officer was treated for trauma.
The wounded man reportedly has four prior arrests. A second man fled the scene, and police were looking for him.