Porn Star Janice Griffith -- I'm Going After Instagram's Biggest Douche ... After Vag-apult Mishap

Porn star Janice Griffith's message is clear -- she's on a legal offensive against Instagram's Biggest Playboy Dan Bilzerian after he threw her off a roof ... and broke her foot.

Janice called in to "TMZ Live" Friday to discuss Wednesday's accident after we posted video -- and even though she danced around the subject of her lawyer ... it definitely looks like she's being coached.

Translation: Bilzerian better get his checkbook ready.

Janice claims she's already missed several jobs -- including a big one for Kink.com -- and she won't be able to work again for several more weeks. The worst part, she says Bilzerian never ONCE apologized for the accident.