McGregor said Mayweather wants to box him because he is "afraid of a real fight."
Conor McGregor is still open to fighting Floyd Mayweather, but he has very specific conditions he wants met for the fight to happen.
"Tell Floyd and Showtime, I'm coming," McGregor said to the crowd while on-stage at a New York City nightclub. "Tell him to go to them Showtime offices. I want $100 million cash to fight you under boxing rules cause he's afraid of a real fight."
Mayweather said earlier this year that he was responsible for starting a rumor that he and the new UFC lightweight champion would fight. McGregor responded to the rumor with willingness to make the match-up happen, despite having no professional boxing experience.
"Floyd's not ready for this," McGregor said. "Much respect to Floyd, he's a solid businessman. What he has been able to do, he's a f------ animal at what he's been able to do but as far as real fighting, as far as true, pure unarmed combat—Floyd don't want none of this."
McGregor most recently defeated Eddie Alvarez on Saturday night to claim the lightweight belt and move his UFC record to 21–3. Mayweather retired with a 49–0 record.
Mayweather responded to McGregor's challenge later on Wednesday.
"A lot of fighters in the sport of boxing may want to retire, but they have to fight because they have to," Mayweather said to USA Today. "I don't have to fight.
"I just made $300 million for fighting Pacquiao. I'm OK. Like I said before, I'm happy with my position. Once again, the money don't make me; I make money. I'm well-off. I make smart moves, and like I said before, I'm happy with where my career has went."