Pogba, 19, made just seven senior appearances for the Red Devils but was viewed as a rising star and a likely first-team regular. The Frenchman's contract expired this summer but United were keen to extend his stay and offered him fresh terms as well as the chance for great first-team opportunities next season.
But a move to Turin now looks on the cards, although the deal has not yet been confirmed by the Italian champions. Ferguson made little attempt to hide his displeasure at Pogba's decision. The Scot told MUTV: "Pogba signed for Juventus a long time ago as far as we're aware. "(It) is disappointing. I don't think he showed us any respect at all, to be honest."
He added: "I'm quite happy that if they carry on that way, they're probably better doing it away from us."
Pogba arrived at United from Le Havre in 2009 - a move that infuriated the French side at the time. His seven United appearances all came last season and all from the bench. Three of those were in the Barclays Premier League and three in the Carling Cup, with a solitary Europa League match in a 2-1 defeat to Athletic Bilbao.
Pogba is the second highly-rated young player to leave the club this year after the prodigiously talented but controversial Ravel Morrison was allowed to join West Ham in January. The future of a third, Ezekiel Fryers, is unclear. He has also been offered a new contract but has yet to inform United of his decision.
"We haven't heard anything from Zeki Fryers," Ferguson added. "I don't know what's happening there but he's not been in touch with the club. His agent hasn't been in touch with the club and I can only assume he'll be back for training."
On a positive note for United fans, Ferguson hinted there could be further additions before the start of the 2012/13 campaign. Shinji Kagawa and Nick Powell have arrived from Borussia Dortmund and Crewe respectively, but Ferguson remains on the lookout. Asked if he there would be more new blood, he added: "Yes, there's a possibility.
"We're working on one or two things but there's nothing really to tell you to be honest. We always try to get our work done at the end of the season - we spent a good deal of time sorting the deal with Shinji and we'd agreed a deal with Nick Powell before the play-offs which was a good move by us because the boy had an outstanding final at Wembley.
"When you don't get deals done immediately and you're negotiating with a club over a long period, then you can't expect to just snap your fingers and get it done."