Rihanna -- Trolls Steph Curry ... You're No LeBron

Rihanna ... talkin' trash!!

Didn't take RiRi long to go in on Steph Curry after Game 7 -- throwin' a little shade at the NBA's regular season MVP on Instagram.

Rihanna's a HUUUGE LeBron James fan -- and overloaded her social media with tributes to King James after the Cavs took the title ... even calling him "Bae" at one point.

It's good to be the champ.