Salah said Liverpool must return to being a "heavy metal attacking team that opponents fear" after a 4-2 defeat by Aston Villa, which has put a serious dent in their Champions League hopes.
The Egyptian will leave Liverpool at the end of the season after scoring 257 goals and helping the club to six major trophies during his spell in Merseyside.
After his comments, Rooney has ripped apart the winger, who he believes should not be able to say goodbye in his final games for the club this Sunday against Brentford.
"I find it sad at the end of what he's done and what he's achieved at Liverpool. It's not the point for him to come out and aim another dig at Slot.
"He wants to play heavy metal football, so he's basically saying he wants Jurgen Klopp football. Now I don't think Mo Salah can cope with that type of football anymore. I think his legs have gone to play at that high tempo and high intensity.
"If I were Arne Slot, I'd have him nowhere near the stadium in the last game.
"I had it with Alex Ferguson. I had a disagreement and fall-out, and at Alex Ferguson's last game at Old Trafford, he left me out of the squad for that reason.
"He's almost just dropped the grenade and said he doesn't trust and believe in Arne Slot and almost thrown his teammates (under) who are going to be there next season and let them have to deal with that as well and put them into a position."
Liverpool's trophyless season comes to an end at home this Sunday in what is an underwhelming goodbye for the legendary winger, who may not even get his chance to say farewell.