The new guidelines targeted places like Hudson River Park in Manhattan and Domino Park in Williamsburg, where there has been overcrowding on warm days.
"We know we had some parks last weekend that were more crowded than they should have been," de Blasio said. "It was not some stray individuals, it was the physical realities of the parks."
The city will limit capacity at Hudson River Park Piers 45 and 46 and increase NYPD presence and closely monitor Domino Park, according to the mayor.
"We are going to have NYPD working with other agencies, from the very beginning of the day, limiting the number of people going in," de Blasio said. "Obviously offering people face coverings as well, and keeping an eye making sure the number of people never reaches too high a number. And when it does, asking people to move out to make more space."
The discussion comes as protests have emerged over police enforcement of social distancing.
The NYPD has released statistics showing 68 percent of arrests and summonses for social distancing have involved blacks, while 24 percent have involved Hispanics and 7 percent whites.
Mayor de Blasio responded to those numbers, saying "We have to do better and we will."
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