Mayor de Blasio is contrasting the peaceful response to a death in police custody in New York to the violence that has erupted in Ferguson, Missouri.
De Blasio said he is "troubled" by what he has seen in Ferguson after an 18-year-old unarmed man was shot by a police officer.
Mike Brown's death has led to protests that have been forcefully put down by heavily-armed police using tear gas.
Last month, 43-year-old Eric Garner died soon after being put in a chokehold by a police officer on Staten Island.
The resulting protests from Garner's death have not turned violent.
De Blasio praised the NYPD in response to a reporter's question about Ferguson.
He said New York has a tradition "of respecting and properly managing peaceful protest."