Michael Lohan is ripping the new 'Mean Girls' movie for taking a cheap shot at his daughter, Lindsay Lohan ... saying Tina Fey and Megan Thee Stallion went low, just like their box office numbers.

Lindsay's dad tells TMZ ... he's straight-up "pissed" over the "disgusting comment" in the reboot ... but he's finding some solace in the flick's opening numbers, which were far lower than the OG's debut weekend way back when.

Michael's talking about Megan's "fire crotch is back" line in the new movie ... which references a famous TMZ clip from way back in 2006, when Paris Hilton's oil heir buddy Brandon Davis called LiLo a "fire crotch" multiple times on camera.

Lindsay's dad is also pointing at the fact the new 'Mean Girls' musical made $28 million at the box office opening weekend as a bit of karma.

The original version made $24.4 million on its opening weekend in 2004 -- and while that's lower ... it's actually not bad when adjusted for inflation. By today's standards, it'd be closer to $40 million ... not to mention the $86 mil it grossed domestically through its theatrical run.

Basically, ML is betting the new 'Mean Girls' won't hold a candle to his daughter's initial take on it when it's all said and done. Michael also tells us he would never see the new 'Mean Girls' ... and while he says he'd love to clap back at Megan, Brandon and Tina, specifically ... he tells us he's taking the high road and not getting in the gutter with them.

Lindsay's father adds ... "I will say this however, NOBODY can replace Lindsay or the original cast in that film. Nor can Megan replace Lindsay in the new Planet Fitness commercial dressed like a stripper in a fitness commercial."

Of course, what he's referring to there is the fact that Lindsay did some PF commercials a few years ago ... and now, MTS is doing them as well -- the implication being, she's kinda riding Lindsay's coattails, and not doing it nearly as well as she did.

Bottom line for Michael ... back off from his kid, 'cause he's ready to pounce in her defense.

Papa Bear's growling here ... for better or worse.