At the moment, he's not sure the promotion even wants them in the same building.
Diaz was in attendance at McGregor's lightweight championship fight at UFC 205 last weekend -- but not at the UFC's request. Diaz, who split two meetings with McGregor earlier this year, asked president Dana White for tickets via text message, but he was told there wasn't room.
"As soon as [McGregor wins], hundreds of people are turning around and staring at me," said Diaz, who watched from a club box at Madison Square Garden. "I'm like, 'Hey, what do you want me to do? The UFC didn't even want to give me tickets to this fight. I think they gave Nick Jonas my seat."
Diaz, 31, submitted McGregor via rear-naked choke at UFC 196 in March. The two fought again at UFC 202 in August, with McGregor claiming a five-round decision.
The rivalry was a huge financial success. Shortly after UFC 202, officials told ESPN.com that those two McGregor-Diaz-headlined events accounted for two of the top three pay-per-views of all time.
Immediately after winning the second fight, McGregor (21-3) said he would eventually fight Diaz a third time at 155 pounds -- where he just won the title. But Diaz doesn't know if it will happen.
"The UFC knows that's a bad idea for him," Diaz said. "Why didn't I get tickets to this fight? I said, 'I'll leave him alone. I don't want to fight the guy. Just let me get a seat.' Me and my brother, they didn't want to let either one of us in here.
"They want to hide me out, I think. Put him on more of a pedestal than they have already. It's whatever though."
Diaz (19-11) has previously stated the only fight he's currently interested in is a third fight against McGregor. He said he's still not in a hurry for any fight and has, so far, not been approached about one.
A UFC 209 PPV has been scheduled for Brooklyn's Barclays Center on Feb. 11. It's an obvious date to book Diaz and his older brother, Nick, as they have made those numbers famous by representing Stockton, California's 209 area code. Diaz said there have been no discussions regarding that event.
As far as McGregor's history-making win against Eddie Alvarez, Diaz applauded the Irishman for "doing his thing" but said they both still know who has the edge in their fights.
"People question me, 'Hey, when you gonna fight No. 3?'" Diaz said. "I know that everybody needs to see that. If I'm gonna do something, that's what I'm gonna do -- but I'm not begging for it. If anybody should be asking for the fight, it should be him. He's the one that has something to prove.
"Congratulations to Conor. He did a great job, got the two belts -- but I just know that me and him both know what happened in [our] fights and that 'greatest of all time' stuff needs to just come to an end. I don't remember any of the greatest of all times getting worked over like [he was] in the last two fights."