Nate Diaz BURIES HATCHET WITH BIEBER ... Let's Selfie, Bro

Talk about dodging a bullet ... Justin Bieber has made peace with the man who wanted to slap the blonde off his head, Nate Diaz -- and to prove they're cool, they took a selfie together.

Bieber and Diaz came face to face at JB's concert after-party at Warwick nightclub in Hollywood late Wednesday night.

It was an interesting situation considering Diaz recently fantasized about delivering a Stockton Slap to Justin's head ... after Bieber criticized his fighting style on social media.

But last night it was all love ... no violence ... and Diaz tweeted, "All good doe 100."

Close call tho ...