Bieber's Video Vixen Don't Worry Biebettes ... I'M MARRIED!!!

5/6/2012 6:00 AM PDT BY TMZ STAFF
Rachel Barnes in the Justin Bieber video
Justin Bieber's super hot love interest in his new music video wants the singer's rabid female fans to know she's NOT a threat ... 'cause she's already got a man.

TMZ spoke with Rachel Barnes -- the chick who Bieber can't keep his hands off of in the new video for "Boyfriend" -- and she tells us the chemistry between the two was "only for work."

"Justin and Selena are adorably inseparable and I, myself, am already married" ... adding, "I'm a Belieber, but he's not my boyfriend." 

FYI -- Bieber's fans have a reputation for being a bit ... territorial ... and some have even sent death threats to women who got a little too close to JB ... including Kim Kardashian.

But Barnes -- who got married in La Jolla last year -- says the Biebettes have been cool so far ... adding, "It's been great to be a part of the Bieber madness ... even if only for a song."

Rachel Barnes is married