The former five-weight boxing world champion appeared in Japan at a press conference earlier in the week to apparently promote a contest with Nasukawa, 20, who competes in the RIZIN Fighting Federation.
Nasukawa holds a record of 27-0 in kickboxing and a 4-0 in mixed martial arts.
But in an Instagram post, the 41-year-old said his team were “completely derailed”, after originally agreeing to a small behind-closed-doors exhibition event for “wealthy spectators”.
“Now that I am back on US soil, after a long and disappointing trip to Tokyo, I now have the time to address you, my fans and the media in regards to the upcoming event on December 31 that was recently announced,” Mayweather wrote.
“First and foremost, I want it to be clear that I, Floyd Mayweather, never agreed to an official bout with Tenshin Nasukawa. In fact [with all due respect] I have never heard of him until this recent trip to Japan.
“Ultimately, I was asked to participate in a nine-minute exhibition of three-rounds with an opponent selected by the Rizen Fighting Federation.
“What I was originally informed of by Brent Johnson of ‘One Entertainment’ was that this was to be an exhibition put on for a small group of wealthy spectators for a very large fee.
This exhibition was previously arranged as a ‘special bout’, purely for entertainment purposes with no intentions of being represented as an official fight card nor televised worldwide.
“Once I arrived to the press conference, my team and I were completely derailed by the new direction this event was going, and we should have put a stop to it immediately.
“I want to sincerely apologise to my fans for the very misleading information that was announced during this press conference, and I can assure you that I too was completely blindsided by the arrangements that were being made without my consent nor approval.
“For the sake of the several fans and attendees that flew in from all parts of the world to attend this past press conference, I was hesitant to create a huge disturbance by combating what was being said and for that I am truly sorry.
“I am a retired boxer that earns an unprecedented amount of money globally for appearances, speaking engagements and occasional small exhibitions.”