It happened on the Glendermott Road at around 6.50pm on Friday.
The woman was taking part in a white line demonstration when she was involved in a collision with a passing car.
She was taken to hospital for treatment on injuries which aren't thought to be serious.
There are no further details at the moment.
A statement from the PSNI said: "Police would like to take this opportunity to remind those participating in protests and those organising protests of the dangers of standing in the middle of busy roads during the hours of darkness".