In a way, violence seems appropriate. Fascism has at its root a heavy dose of machismo and meeting it on its own macho grounds can take the wind out of its sails. Right wingers become no longer the tough protectors of the fatherland / motherland, knightly or viking-ly looking out for their white sisters and mothers, but a cowed minority in need of protection from the police.
But, of course, aggressive marches and equally aggressive counter-marches have created a self-sustaining dynamic, with everyone playing out pre-ordained roles. A peaceful, quiet but resolute response to racism could break the pattern in a positive way.