'Step Up' Star Terrence Green to be Disciplined for Gun Gesture on Cop

Terrence Green, best known as Rigo on the 'Step Up' TV series, really stepped in it -- production sources say he mimicked pointing a gun at a cop, and now the network's dropping the hammer.

Sources close to production of the Starz show tell TMZ ... they were filming at the Atlanta courthouse this week when Terrence approached a police officer and used his fingers to gesture like he was pointing a gun at the cop's head.

We're told it seemed Green meant it as a joke -- albeit a tasteless one -- but everyone was appalled by it, including the officer.

A spokesperson for Starz and Lionsgate, which produces 'Step Up,' tells TMZ ... a thorough investigation of the incident's been done, and Terrence "will receive strong disciplinary action."

The rep adds ... "We do not condone any on set behavior, even a gesture, that suggests or simulates violence toward another individual."