A Police Community Support Officer (PCSO) was hit by a car which then drove off in Old Trafford.
The female officer was cycling on patrol on Wordsworth Road South when she was struck on Friday night.
Police said the car turned on to the road from Kings Road and collided with her. The driver stopped, got out and looked back but then drove off.
The officer was taken to hospital to be treated for bruising but has since been discharged.
Det Con Cherylin Allen, of Trafford CID, said: "It appears the motorist actually got out of the car after the incident before driving off thereby making a conscious decision not to help the injured officer.
"While her injuries are not serious they could quite easily have been much worse and I would urge anyone who saw what happened to come forward.
"I would also appeal to the driver to do the right thing and come forward and tell us what happened."
Any witnesses are being urged to contact Greater Manchester Police.