EXCLUSIVE

Conor McGregor has NOT been added back to the UFC fight card ... this according to UFC honcho Dana White.

TMZ Sports spoke to White this morning ... who tells us, "It's not true. We haven't talked to Conor or his manager since the press conference. I don't know why he would tweet that."

He adds, "All the media keeps asking me that. I feel like the scene in 'Step Brothers' when they ask if they can build the bunk beds. I don't know how many more times I can say the fight is off or how many more press conferences I can have saying the fight is off for people to believe it's off."

TRANSLATION -- THE FIGHT IS OFF!!!!