Justin Bieber-- Nailed by Lotsa Cops for Speeding (VIDEO)

Law enforcement sources tell TMZ ... speed was a factor, but Justin was cited for unsafe passing on the right. JB was also given an equipment violation for window tint.

Justin Bieber's passion for fast cars got the best of him Saturday night, when he got stopped by a Beverly Hills cop ... and plenty of reinforcements.

Witnesses tell TMZ, Justin was going well over the 25 MPH speed limit in his new Ferrari when he was spotted on a residential street in Bev Hills.

After the stop, 3 other squad cars rolled up. It's unclear why. We're told Justin got a speeding ticket and went on his way.

He did not ask the cops, "What do you mean?" They were clear.