Mourinho said his players were "masters in complicated football".
"I trust in my work, that is for sure - I have no reason not to trust", he said.
United's limp display irked Mourinho and the manager said overconfidence was key in allowing the beleaguered Baggies to secure just their fourth league win of a terrible Premier League campaign.
"No! Last week I want to win three points, like today".
The disappointing result which were met by severe jeers from the home supporters at the final whistle gifted the Citizens the title with five games to spare.
But he's refusing to look more than one week into the future because it is that mantra that has served him well so far.
They had Jose bloody Mourinho who has never not won a league title wherever he went.
City originally had the chance to win the league against United last week but a win for the Red Devils only delayed the inevitable by eight days.
In the end, Manchester City were deserving champions. It was only three points.
In fairness to Mourinho he grabbed a win away at The Etihad but even a second place finish seems like a serious underperformance given the manner of Manchester City's run to the title. During the week I was trying to fight that.
Light Winds with Cool Temperatures for Monday
They will pick back up on Friday and into the weekend ahead of yet another upper-level low that will move into the Rockies. Under continued bright skies, Wednesday and Thursday will feature highs in the deep 70s to locally, on the mainland, 80s.
"But you need time. In my experience you don't win titles with inconsistency". "One of the things we have to improve is our consistency".
City captain Vincent Kompany led the celebrations, tweeting: "Champions!" It is hard to imagine City's players and Guardiola being too bothered by that, though.
Considering this was their first victory since January and just their fourth in the league this season, perhaps that's understandable.
"Second position was not done before the game", Mata told United's website. It's a hard achievement, and I'm proud of the team and everyone involved. "You know, people, you like stories".
"I have won titles". I suppose my team-mates will roll their eyes a little bit but I kind of want to see what the reaction is now.
The 47-year-old also took the German title three times with Bayern Munich, but he believes the unique strength in depth and physical demands of the Premier League makes this triumph among his very best. "It was not done even if we won. We're still super-happy, but there is so much to do before we unlock our full potential".
However, Premier League survival still looks unlikely for the Baggies, who are nine points adrift of 17th-placed Swansea with four matches remaining.
71 minutes into the game, Jay Rodriguez managed to break the deadlock for the away side as he calmly headed a loose ball from a corner kick into the back of net, taking the lead for the Baggies. "One team was dominant in Germany and one had [Lionel] Messi, but we are nothing without the team".
Pep Guardiola's side were on the brink of securing the title after an impressive performance in beating Tottenham Hotspur 3-1 at Wembley on Saturday. "These guys are fantastic, awesome - they are incredible". "After what this club has done in the last ten years, in terms of creating facilities and making it bigger, it will happen". City has won seven trophies, adding an FA Cup, two League Cups and an FA Community Shield to their league titles.
Paul Pogba's two goals against City felt like a defining moment for the France midfielder during a season which has had more downs than ups.