White joined the guys on the "TMZ Sports" TV show (airs tonight on FS1) -- and we asked about Nate's Instagram post where he called himself "The Real Champ" and vowed to return to fighting in "May or June."

"I'll tell ya what," White said ... "I’ll call him today and make him an offer."

"I will make Nate Diaz an offer to fight today."

White says he's not sure who he'd match Diaz up against -- "I gotta look at the rankings and see where everybody is."

What about a 3rd fight with Conor McGregor? Dana isn't ruling it out ... but says that fight ain't the priority for Conor.

"I think people would rather see Conor come back and either fight Tony [Ferguson] or Khabib [Nurmagomedov] -- whoever wins -- and the Nate Diaz fight isn’t going anywhere. We can do that thing any time."

What about Nate vs. Tyron Woodley? Dana says he has other plans for the welterweight champ.