The traffic policeman has been suspended pending an inquiry into the incident which was caught on camera, a senior police official said.
The incident happened this afternoon when Nagappa removed a rope at a crowded junction on Bellary road, breaking the cordon to make way for an ambulance carrying blood for an emergency operation at a hospital, as the vehicle was caught in a traffic snarl.
He said as soon as the ambulance moved, the Sub Inspector came from the other side, started abusing him and tried to thrash him and push him around.
Traffic in several parts of the city was thrown out of gear after early morning rains.
Nagappa said the Sub-Inspector has sought apology and he does not want to take the issue any further.
However, DCP Traffic East (Bengaluru) Baburajendra Prasad said an inquiry has been ordered and the Sub-Inspector suspended.