flatly denies instigating the fight that went down in a Canadian Denny's ... in fact, he claims he got sucker punched and plans to sue the guy who allegedly socked him.

Manson's manager tells TMZ the rocker was enjoying his late night meal when two girls approached him and asked for a photo. Manson says he obliged and never called either woman a "b!$%h" ... as the alleged puncher claims. 

Marilyn says the guy came out of nowhere and hit him in the face. Manson says his security grabbed the guy, who then began screaming about blowing up Manson's next concert. 

Manson also claims the attacker elbowed his makeup artist in her face. He says they're both going back to cops in Alberta to press charges

Read more: http://www.tmz.com/2015/04/07/marilyn-manson-suing-fight-d