Headers from Romelu Lukaku and Nemanja Matic on either side of half-time helped United bounce back from their humiliating Champions League exit to Sevilla at Old Trafford in midweek.
McTominay's 'worst match' yet
Asked which players he wasn't pleased with, Mourinho responded that he would "prefer to name the good ones" and highlighted Man of the Match Matic as a stand-out performer.
"Matic was an island of personality and quality and reaction to the defeat of last Tuesday. Of course, not surrounded by water, surrounded by other people that did a positive job."
Scott McTominay has shined since becoming a regular fixture in the first team under Mourinho, but his manager labelled his performance on the night alongside Matic as the "worst" he's seen from him.
"For example, Scott [McTominay] played on [Matic's] side and played the worst match since he played with me in the first-team. But he is a Manchester United player for sure because he's the player that made mistakes, passed the ball so bad tonight, lost so many passes.
"But, big personality to cope with a mistake, big personality to say and to think I am not playing well but at least I will do the basic things of the game. Which is to keep position, give balance to the team, recover balls, don't make defensive mistakes."
Some were 'scared to play'
Although the Red Devils boss saved a little bit of praise for 21-year-old McTominay, he accused "a few" of his players of being "scared to play" just days after the 2-1 loss against La Liga side Sevilla.
"But a few of the other guys were scared to play, I cannot say much more. I think is the relation with personality, is the relation to trust, is a relation to class.
"When the sun is shining and is a period in football where everything goes well; you win matches, score goals, everything goes in your direction, every player is good, every player wants to play, every player wants the ball, every player is confident and every player looks amazing.
"When it is dark and cold, and that in football means a period of bad results or a bad result like a couple of days ago, not everybody has the confidence and the personality to play really.
"Because to be on the pitch and touch the ball every five minutes, anyone can do it. But to be on the pitch and say give me the ball because I want to play, that's a little bit more difficult, because not all of them were able to do it."