The Argentine midfielder completed a move worth £44.3 million to PSG after spending just one year out of five years with United. Already signing a four-year deal with the Ligue 1 side.
His relationship with LVG was reported to be strained in the second half of the season after pelvic and hamstring injuries hampered his involvement.
He also hinted that his family was unhappy at Manchester after an attempted break-in.
“I’m happy because I know my wife and child will be happy in Paris,” he said.
“It wasn’t just my decision to leave. If I left it was also because they decided to sell me.”
He added: “The three parties agreed. Me, Manchester United and PSG agreed the deal.”
PSG president Nasser Al-Khelaifi said: “I’d like to thank him for choosing PSG.
“I know a lot of big clubs were interested because he is a great player.
“He’s already won the Champions League with Real; I hope he can do it with us.”