Drake floored the masses when he brought Tupac Shakur and Snoop Dogg into his beef against Kendrick Lamar via AI ... and Pac's brother thinks it was a step too far in the ongoing beef.

Mopreme Shakur, Tupac's brother tells TMZ Hip Hop that his issue with Drake using an AI Tupac voice is that he weaponized it ... all for a rap battle.

Mopreme tells us Drake using Pac's voice is like bringing out a tank, or even going with a nuclear option -- and he thinks the battle should be 1-on-1 ... with no outside help.

Of course, Mopreme isn't naive to the fact Kendrick is a West Coast legend himself inspired by Pac ... and Drake is trying to push some buttons.

Jay-Z famously said he'd kill "ants with a sledgehammer" in his "Takeover" diss against Nas, and Tupac himself outlined the "Secretz of War" with a totalitarian attitude -- so, Drake might be following their lead by using Pac's voice.

Fans defending Drake pointed out Kendrick famously used a Tupac interview to close out "To Pimp a Butterfly" -- the album J. Cole failed to slam -- but Mopreme agrees with that move because it was an homage.

He has nothing but love for Kendrick, Drake and Cole ... and says they all need to make sure the rap battle remains sport, and doesn't escalate into physical violence.

Mopreme says of course he loves hearing his brother's voice ... just not in a battle.

For his part, Snoop was left speechless when fans cornered him for a reaction.

Mopreme admits Drake's song made him realize AI "is a hell of a tool" ... and in Pac's case, he's worried younger generations might confuse the artificial Pac with the real deal.

Suge Knight's reaction was similar to Mopreme's ... he says Pac was king and should never be stooped down to do a pawn's bidding.