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Dana White says he will not offer Conor McGregor a stake in the UFC to lure the fighter out of retirement ... telling us, "That's never gonna happen."

McGregor announced his retirement on Twitter Monday night -- days after he reiterated his demands to get a slice of the UFC as a part owner instead of a fight paycheck.

White appeared on "TMZ Live" on Tuesday and said he's NOT trying to go to war with Conor -- but he ain't giving away ownership stakes either.

White says if Conor wants UFC ownership, he needs to BUY stakes in the company like everyone else.

"Listen, if you want to own a piece of the company, you have to put up the money to buy a piece of the company," White explained ... "That's how it works."

White says he was surprised by Conor's retirement tweet -- "it came out of nowhere" -- and insists he and Conor are still on good terms.

"I've never had a bad conversation with Conor McGregor since he's been in the UFC."

White is also not concerned about the state of the UFC if Conor is serious about retirement ... saying there will ALWAYS be big stars who take over when other stars leave.