"They left me out because they said I wanted to leave. That is disrespect," Pogba, who left United in July 2012, told the BBC.
"Maybe they didn't think they were making a mistake."
When Pogba left United, then-manager Alex Ferguson had said he was "quite happy" to offload the player who the Scot accused of not "showing us any respect at all".
Pogba, 21, made just seven substitute appearances for United before heading to Italy.
"Manchester United is a big club but you have to think about yourself," Pogba added.
"You have to play. The coach told me there would be space to play, but I wasn't playing.
"I was training alone for one week. They told me to go in the gym. I said 'I am not an athlete, I am a footballer'."
Since his move to Italy, Pogba helped Juventus win the Serie A title in 2013, a feat they are poised to repeat again this season.
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