Peaceful demonstrations of social dissent stem from social frustration.
Social frustration as of late stems from injustice, inequitable exercise of the law/judicial system, and quite frankly: Social hypocrisy and systemic corruption.
Peaceful demonstrators are not to blame for the very few extremists who transform their social frustration into vandalism and/or violence.
If anyone is “to blame” for the violence of an extremist (other than the clear blame due to the extremist himself); then look to the root cause of the social frustration in the first place.
Cure the cause for the social frustration; and then there will be no demonstrations of any type of social frustration of any sort; for there will then be no cause for social frustration.