An activist group is delaying Barry Diller’s “Hollywood on the Hudson” park project by demanding reams of documents to try to prove that it was designed without public input.

The City Club of New York is opposed to the 2.7-acre development off West 13th Street, arguing that the area will become too commercialized.

The public park built on Pier 55 is set to host events curated by Oscar-winning producer Scott Rudin.

Diller and his fashion-designer wife, Diane Von Furstenberg, are contributing tens of millions of dollars toward the development.

David Paget, the lawyer for the state entity overseeing the project, told a Manhattan Supreme Court judge Tuesday that Diller and his wife should be commended for their philanthropy.

But Judge Joan Lobis, who disclosed that she frequently cycles along the Hudson River, questioned whether charging parkgoers for performances is a privatization of a public space.

Paget said there’s precedent for the model, citing Randall’s Island, which hosts ticketed events such as the annual electronic music festival, Electric Zoo.