Robert Lederman and Jack Nesbitt say that allowing only about 120 vendors in Union Square, Battery Park, the High Line Park and parts of Central Park is unconstitutional.
In the lawsuit filed in Manhattan federal court late Friday, the artists argue that greenmarket and commercial vendors create more congestion than the roughly 300 art vendors who work in those parks now.
A city Law Department spokeswoman says it is awaiting a copy of the lawsuit, but will review it thoroughly.
The city had slightly raised its proposed cap this week after opposition to the limits from artists. It's scheduled to take effect July 19.