Police have come under fire after footage of an arrest emerged showing four Bendigo officers pinning down a 12-year-old boy as people looked on and protested.

The video, filmed by a bystander watching the arrest, shows the boy being pushed to the ground and restrained by officers who order him to "shut up".

"All I f---ing did ..." the boy begins before he is cut off.

"Shut up," one officer in the video is heard to respond. "You had your opportunity. You're not going to hurt my members or me, OK?"