The Hollywood actor uploaded a homemade clip that includes him lip-synching to 'Boyfriend', while being joined by his Spring Breakers co-star Ashley Benson.
Back in October, Franco denied rumours that he was dating Benson, as well as their fellow Spring Breakers star Selena Gomez.
"Those are [Justin] Bieber's girls and I wouldn't dare tangle with the Biebs," he said at the time. "I heard he wants to kick my ass. Yikes!"
Bieber is believed to have split from his girlfriend Gomez over the New Year, after they briefly reunited for the festive period.
Meanwhile, Franco will star as Oscar Diggs in new blockbuster Oz: The Great and Powerful, which is released in cinemas on March 8.
Watch the trailer for Oz: The Great and Powerful below: