Mourinho, now the manager of Inter Milan, wishes he had chosen to take up the opportunity to leave the Blues after their 1-0 win over the Red Devils at Wembley in May 2007 as he could have left the club on a high.
Speaking in a video released by Ford's FeelFootball.com, Mourinho said: "If there is a moment in my career where I regret a decision it was clearly the day after the FA Cup final - when my agent told me 'Club X' want you tomorrow and I told him no, I love it here and I don't want to go, I want to stay.
"That's the moment I regret. After that day, after that final, I should (have left) Chelsea and I would have the chance in Wembley to say goodbye to the fans and to say goodbye to English football. So that's a moment I regret because the next season lasted only a couple of months."