My experience:
Liberals and leftists are a generally peaceable lot. They're tolerant, and prefer non-violence, passive resistance, &c.
It's the authoritarian right wing who are intolerant of disorder, bristle at a lack of respect for 'sacred' symbols and social conventions, often resort to violence, and prefer a show of strength to non-violence.
In my experience it's the police, angry at disorder and disrespect, who escalate peaceful protests into violent confrontations.
From Wiki:
Right-wing authoritarianism is defined by three
attitudinal and
behavioral clusters which
correlate together:
Authoritarian submission — a high degree of submissiveness to the authorities who are perceived to be established and legitimate in the society in which one lives
Authoritarian aggression — a
general aggressiveness directed against deviants, outgroups, and other people that are perceived to be targets according to established authorities.
Conventionalism — a high degree of adherence to the traditions and social norms that are perceived to be endorsed by society and its established authorities, and
a belief that others in one's society should also be required to adhere to these norms