NEW YORK (CBSNewYork) -- Mayor Bill de Blasio is urging protesters to call out and avoid agitators after violence has broken out at several demonstrations this week.
Nineteen people were arrested during protests Thursday night.
Hundreds of people marched in Manhattan, many for different reasons, and while most were peaceful, there were some who clashed with police.
One officer was pushed to the ground with a chain pressed to his neck.
"If you see folks among you doing violence or planning violence that have got chains or hammers or anything in their bag, you need to separate from them and you need to point out what they're doing because that's not what most protesters are about," de Blasio said Friday.
When asked about aggressive policing tactics, the mayor said video clips do not necessarily tell the whole story.
He said the tactic known as "kettling," where protesters are surrounded and prevented from dispersing, is not acceptable.
The mayor says the NYPD's goal should always be to de-escalate and use as little police presence as possible.
MORE FROM CBS NEW YORK
- New York City's New Quarantine Travel Rules Begin, New Jersey Adds States To Advisory List
- Water Main Break Swamps Cars In Queens: 'The Water Just Went Up And Up And Up'
- Commanding Officer Of NYPD Office Of Equal Employment Opportunity Accused Of Posting Racist, Anti-Semitic Comments Online
You can get the latest news, sports and weather on our brand new CBS New York app. Download here.
for more features.