Bridget Marquardt doesn't think Jessica Biel should think twice about the message she got from Hugh Hefner's ex ... and should stay in the upcoming Playboy movie.

Bridget sat down with TMZ's Charlie Neff on "The TMZ Podcast" to discuss the digital drama going down ... and she tells us Crystal Harris was just looking for attention when she messaged Jessica.

Crystal slid into Jessica's DMs asking her to reconsider playing Hef's wife in "Playmates," referencing what she calls "troubling concerns regarding minors" and saying she experienced "sexual, emotional, financial and physical abuse" during her marriage to Hugh.

But Bridget tells us that she doesn't even think the actress should respond, let alone drop out of the film.

Crystal and Hef tied the knot back in 2012 ... and was with him until he died five years later.

And as for Bridget, she starred along Hugh's other girlfriends Holly Madison and Kendra Wilkinson in the reality show "The Girls Next Door."

It's worth noting that while Jessica has been cast as Hef's wife in the upcoming film, her character's a fictional one ... meaning she won't be specifically portraying Crystal or any of of Hugh's other real-life wives.

Basically, Bridget says the DM is nothing for Jessica to get her Playboy Bunny tail in a twist over.