Protestors should protest legally. They shouldn't block roads. They shouldn't break windows. They shouldn't burn buildings. When they don't they should be broken up/arrested/charged with the crimes they break. This goes for all sides.
I absolutely don’t believe any of the exception I would list actually apply in this case — and even if I did I would still apply the “arrest people who break the law” part because of how fundamentally important I regard rule of law — but there are some occasions (most civil rights battles, wars for independence) where facing a conviction is worth it because the system won’t even take you seriously otherwise.