After coming face-to-face with Pacquiao during his tour of Japan, Mayweather released a video on Instagram accompanied by the message: "I'm coming back to fight Manny Pacquiao this year, another nine-figure pay day on the way!"
The American, 41, can be heard shouting in the video: "I'm coming back in December!"
Mayweather is unbeaten in 50 career contests, having stopped UFC star Conor McGregor in a lucrative Las Vegas bout last August.
Mayweather defeated Pacquiao by unanimous decision at the MGM Grand in May 2015 in a long-awaited bout between the pair.