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.
Pacquiao, 39, who has recently been connected with a fight against British star Amir Khan, knocked out Lucas Matthysse in Kuala Lumpur in July, bouncing back from a loss to Australian Jeff Horn, which had been his seventh career defeat.
Matchroom, led by Eddie Hearn, have been in talks to sign the legendary Pacquiao after the Filipino, who is WBA welterweight champion, left long-term promoter Bob Arum.
Photo Getty Images. Caption: Retired boxing legend Floyd Mayweather Jr