The United manager was speaking ahead of his side's FA Cup semi-final against Tottenham, and he played down claims that this game could define United's season. Mourinho's side have missed out on the title, and the cup is their only shot at silverware this season.
"Can you say the three teams that are not going to win the FA Cup are going to fail?" he asked. "I think it's too harsh."
"Praise the winner and we're going to try to be the ones."
"Many clubs had positive seasons, like us, like Tottenham, like Liverpool," he continued, making it clear that due to Manchester City's quality it is harsh to judge the success of a season on trophies alone.
"But it was impossible, because City were really good and consistent and will reach a number of points that makes it impossible."
"Give no chance to the opponent, that's what Manchester City did."
United will look to be active in the transfer market in order to bounce back next season, but Mourinho thinks that City have a good chance of winning the title again next year regardless.
"If they do the same number of points [in 2018-19], if they get into the 90-something points, it will be almost impossible again," he claimed
He went on to liken the situation to his time in the Spanish league as Real Madrid boss. "I was champion in Spain with 100 points and Barcelona had 91 points," he said. "91 points was a failure for Barcelona?"
"I don't think it was, but the other guys did 100 points."