Ronda Rousey's Trainer Shrugs Off Mom's Attack ... 'That's Her Opinion'

Ronda Rousey's trainer says he's not bothered by the scathing verbal attack Ronda's mom directed at him over the weekend ... saying Ronda's opinion is the only one that really matters.

Ronda's mom AnnMaria De Mars went on Submission Radio and launched new insults at Edmond Tarverdyan -- calling him an "idiot" and a "fraud" ... and begging her daughter to cut ties with him.

But Tarverdyan tells TMZ Sports ... he can't focus his energy worrying about what Ronda's mom thinks -- he's got more important things at hand ... like training her for her Holly Holm rematch.

"It's just her opinion," Edmond says ... "I'm just here to train Ronda and it really doesn't matter."

"Ronda knows who I am. I am her trainer and that's really about it."

As for Ronda, she stood by Edmond the first time her mother went after him in public -- and it seems she's committed to him this time around as well.