The Westchester District Attorney’s Office nabbed Pace University’s cultural-affairs director with a stash of kiddie porn after a detective answered the man’s Craigslist ad seeking a “nubile girl next door,” authorities said yesterday.

David Watson, 62, a Shakespeare buff who spent years organizing children’s theater events in Westchester, allegedly thought he was meeting a fellow pedophile to discuss their mutual interest in child porn at an Elmsford motel Saturday.

His attorney claims the images don’t constitute child porn.