Drew Brees got clean finessed by his jeweler -- and the only way to stop it from happening again is to get some gangstas on his squad ... so says rap star Rich The Kid.

We broke the story ... Drew filed a lawsuit against San Diego jeweler Vahid Moradi claiming the bling he bought from Moradi over the years -- around $15 million worth -- was actually worth MILLIONS less.

For his part, Moradi and his attorney Eric M. George deny all wrongdoing and say Brees has no one to blame but himself.

Rich is no stranger to ice (duh, rapper) so when we got him in ATL we asked him what he thought about the whole ordeal, and it's clear he thinks Brees took an L.

"He got finessed."

FYI -- for those of you who don't know, being finessed means to get played. If you don't know what getting played means it means to get duped. If you don't know what duped means we can't help.

All is not lost for Drew (what's a couple million right?) ... because Rich had advice to keep it from happening again.

"He needs some gangstas with him."