About 80 Chelsea residents yesterday demanded a 10,000-square-foot city parking lot be turned into a park.

“Parks are a community’s basic need,” said Matt Weiss, 34, president of Friends of 20th Street Park. “If you build it, they will come.”

Supporters hung up signs reading “Looking for a park . . . RIGHT HERE!” beneath the locked lot’s barbed wire on West 20th Street near Seventh Avenue.

The lot is currently used for Sanitation Department vehicles, but the city plans to build affordable housing there, Weiss said. A Sanitation spokesman said it gave the Department of Housing, Preservation and Development the lot last November.

“When I wanna go to a park, it’s too far,” said Harvey Vanblerkom, 8, in his Little League uniform. “You can’t play ball on the High Line.”