He told The Times: "I didn't want to sign a contract as Ferguson didn't play me, even though there were no midfielders there.
"He obviously thought I didn't deserve the contract I asked for, and didn't put me in the team even though he had no midfield players. It was his choice.
"United were short of players like me, but it was the manager's decision. I couldn't do anything about it. I was frustrated because he spoke to me a few times and said I was nearly there.
"I told him 'If I don't play then I can't get any experience and see how far I have to go'. I played a few cup games but he didn't want to give me a contract and they just let me go."
Pogba insists money never came into his thinking when deciding to leave Manchester for Turin, but says the return of Paul Scholes was the final straw.
He said: "When I saw Scholes come back part of me was really happy as he's a legend, but I knew it was the end of me. The manager thought Scholes had to play, not me, and after that I had to leave. Maybe Ferguson will regret it now, but I don't think about Manchester United any more. I have no regrets about leaving Manchester, none at all."