"It is striking" that a "very high level of violence" was seen in protests in France in recent years over cost of living, pension reform and last week's police killing of a teen driver, E.U. Justice Commissioner Didier Reynders told Belgian public radio RTBF.
"That really needs to be looked at because it poses a problem," the commissioner, a former Belgian prime minister, said.
Reynders said the issue was with "a certain number of police officers... (and) the behaviour of people who have the right to freely protest - that's a fundamental right - but not to loot shops, to destroy stores, not to destroy public equipment".
He said that Brussels sees "probably two or three demonstrations a day, but these demonstrations - which fortunately aren't all violent - are handled in a way that perhaps relies more on prevention... rather than direct confrontation."
Reynders is expected to present the European Commission's annual report on rule of law in the 27 EU countries on Wednesday.
It looks at media freedom, the functioning of courts and the fight against corruption, and offers a series of recommendations.
However, law enforcement and fundamental rights do not come under its scope.
Two E.U. countries, Poland and Hungary, are in Brussels' sights for "very big deviations when it comes to rule of law," Reynders said.
They have already had E.U. funds frozen pending reforms to improve the independence of judges and to battle corruption.