The incident happened around 10:30 p.m. at 12th Street and Broadway in Manhattan.
Chiara de Blasio, 25, was allegedly in the road with at least 100 other people and refused to leave when officers told the crowd to move.
Sources say that she was not observed throwing debris, but she was seen yelling.
Police confirm she was placed under arrest for unlawful assembly.
She was given a desk appearance ticket and released around 8 a.m. Sunday.
The mayor has not commented so far.