There are a number of things the police can do besides resort to violence (which they are authorized to do if necessary). While news reports highlight violence, the vast majority of police interactions in the USA are non-violent. Just having the police present as representatives of law enforcement will change the tone of the interaction. The police can also act as mediators. Yes, there is the possibility that the police may have to resort to force, but that's not the only possible—or likely desired—result.