The “Entourage” arriviste has reportedly been warned to keep away from Nobu Matsuhisa ‘s restaurant empire after boorish behavior in Aspen during the recent U.S. Comedy Arts Festival.

“He was asked never to return to Matsuhisa in Aspen by a manager,” alleges a snitch.

“He came in with a large group of 12 or more without reservations and asked for a table. It was a very busy night, but a table, although cramped, was provided. On his way out, he made a nasty comment to the manager: ‘Thanks for nothing.’”

Piven was at the HBO-sponsored festival to appear on a panel with fellow “Entourage” stars. Allegedly his tip also left something to be desired.

“He left a DVD of the first year of ‘Entourage’ to one of the waiters. [An employee] ran up the stairs and hurled it at him as he was leaving.”

The actor was tartly advised to steer clear of Nobu outposts in New York and Los Angeles as well (although they are managed separately).

Piven said through his rep: “I’m such a fan of Nobu and all of his restaurants. I had a great dinner at the Nobu in Aspen. As always, the meal was excellent and the service was great.”