Ronda Rousey's Training Vin Diesel's Daughter ... 'Creating a Beast'

Vin Diesel's 7-year-old daughter might soon be able to rip your arm out of its socket ... 'cause she's training with Ronda Rousey ... and Vin says he wants her to be a "BEAST."

Diesel and Rousey co-starred in 'Furious 7' together -- and obviously became close enough friends that Vin asked her to mentor his little girl in the ways of ass-kickery.

"I made a decision early on that I was going to do everything in my power to empower [my daughter] to handle [trouble] herself," Diesel told WENN.

"Because of her 'auntie' Ronda Rousey she is now an orange belt with stripes in Judo. I'm dealing with it early. I'm creating a beast and I want her to be able to say no means no."

Just 12 more years 'til she's around UFC age ... just sayin'.