Auburn deputy mayor Salim Mehajer allegedly threatened the family of Sydney siege survivor Joel Herat after a dispute with his father at a Burwood gym.

Mr Herat's father, Bruce Herat who works at the Anytime Fitness gym on Railway Parade as a personal trainer, was allegedly confronted by Mr Mehajer after he requested he stop dropping weights on the gym's floor.

After following Mr Herat to his car, Mr Mehajer allegedly confronted the 52-year-old, saying: "Don't you know who I am?" Channel Seven reported on Saturday night.