API Balaji Dahifude sustained serious injury to the head and other parts and is in a critical condition at the ICU of Cooper hospital, they said.
The incident occurred around 2.50 AM when Dahifude was manning the roadblock alongwith his colleagues at Seven Bungalow on JP road.
The biker, Shahid Mahmood Dongerkar, a Disc Jockey (DJ), and a resident of Versova village in suburban Andheri, has been arrested.
Dongerkar, according to police, was returning from a party with his friend on the motorcycle.