George Ferguson has been caught on video calling a protestor "sick" and "a jerk".
An environmental protestor dressed as a fly confronted the Bristol Mayor about pollution at the Avonmouth Make Sunday Special event.
The free community event is one of several held around the city. The protestor, Ian Robinson, is an Avonmouth resident who campaigns on pollution in the area. He confronted the mayor with accusations of closing public services and diverting money into "bread and circuses".
The mayor told him people were enjoying the event and that he should "just go away".
The mayor has yet to comment on the incident, but tweeted about the event being a success.