The incident was reported Saturday evening around 5:30 pm.
As a couple was being arrested, video shows one of the officers break away from that arrest to walk up to a bystander with his taser drawn -- swearing and telling him to move back.
He then tackles the bystander to the ground and repeatedly hits him.
The NYPD says its Internal Affairs bureau is investigating and the officer has been placed on modified duty.
Mayor Bill de Blasio said he was disturbed by the video and called the behavior unacceptable.
Saw the video from the Lower East Side and was really disturbed by it. The officer involved has been placed on modified duty and an investigation has begun. The behavior I saw in that video is simply not acceptable.— Mayor Bill de Blasio (@NYCMayor) May 3, 2020
The Legal Aid Society condemned the NYPD for the incident and is calling on the department to release the names of all officers involved and for their immediate discipline.
"City Hall and the NYPD need to seriously reconsider social distancing enforcement that leads to escalations involving the use of tasers and violent assaults," said Tina Luongo, Attorney-in-Charge of the Criminal Defense Practice at The Legal Aid Society. "What is equally disturbing is that some of these officers - who were ostensibly enforcing social distancing laws - were in violation of those same very laws themselves by not wearing protecting masks, endangering the lives of all New Yorkers around them."