The mayor made the comments during a Sunday appearance on CBS’ “Face the Nation,” following Saturday’s demonstrations against police brutality.
The demonstrations started Saturday with a march around noon. Later, a separate demonstration near downtown resulted in two dozen arrests, 17 injured officers, and at least two injured protesters.
Lightfoot said that agitators “have embedded themselves in these seemingly peaceful protests and come for a fight” though the clashes were “over very fairly quickly because our police department is resolved to make sure that we protect peaceful protests.”
Chicago Police Department Superintendent David Brown said that some in the group used black umbrellas to make it harder for police to see them, pushed officers and assaulted them.
In one video released by Chicago police, a person swinging a skateboard strikes an officer.
Activist groups and some elected officials, meanwhile, accused police officers of using aggressive tactics, including spraying the crowd with a chemical irritant and striking protesters with batons.
“The march was peaceful until CPD and other law enforcement agencies began an all-out assault on protesters,” said a Sunday statement from youth activist group Increase The Peace.
The march came about a week after a police shooting of a black man in the city’s South Side prompted large crowds of people to go into Chicago’s downtown shopping area, where they smashed windows of businesses and took merchandise from stores.
A social media post had falsely claimed that police had fatally shot a 15-year-old, when in fact, the man was 20 years old and did not sustain life-threatening injuries.
The Associated Press contributed to this report.