The crowd descended on Foley Square near New York police headquarters on Thursday, carrying placards saying "Black Lives Matter," "Racism Kills" and "Ferguson is Everywhere."
Several helicopters flew overhead, monitoring the swelling crowd as they chanted "no justice, no peace." It is the second consecutive night that demonstrators took to the streets of New York in fury at a grand jury's decision on Wednesday not to indict the officer over the July 17 death of Eric Garner.
Protests have been overwhelmingly peaceful but police arrested 83 people overnight and have been braced for possible unrest after a similar decision in Ferguson, Missouri last week sparked riots.
Police arrested 83 people overnight and have been braced for possible unrest
The St Louis suburb, a two-hour flight from New York, has been a hub of protest and racial tensions since unarmed black 18-year-old Michael Brown was shot dead August 9 by a white police officer.
Thursday's protest began in Union Square, where activists lay on the ground shouting "I can't breathe" and "hands up, don't shoot," rallying cries of the protests against Garner and Brown's deaths.
"We will not stop until something is done," 40-year-old protester Jonathan told AFP in Foley Square. "We cannot tolerate police impunity. The government has to react. They had a video showing what happened, what else do they need?"