The plan, still-born after first being floated in February, received cautious backing from Asia last week but United's fiery manager insisted there was no room in the calendar.
"I don't think there will ever be a 39th game and I don't believe there should be," the Scot told reporters on Tuesday after United's arrival in Japan for the Club World Cup.
"Certainly I'm not in favour of it. You look at our domestic programme allied to our cup competitions -- it's impossible."
Ferguson made no secret of his disgust when the Premier League initially made the proposal, claiming the clubs had not been properly consulted.
Asian soccer chief Mohamed Bin Hammam, along with FIFA president Sepp Blatter and UEFA chief Michel Platini, were also vociferous opponents.
However, Hammam has since softened his stance and Premier League boss Richard Scudamore visited Tokyo last week to announce a tie-up to help boost the game in the continent.
The exchange could eventually pave the way for games to be played in Hammam's giant territory, although there is expected to be strong resistance for England's top clubs.
Ferguson's side play Japan's Gamba Osaka in Yokohama on Thursday in the semi-final of the Club World Cup. The final takes place on December 21.
