Pogba started on the bench for the second successive game in the 4-1 stroll over Fulham on Saturday and remained an unused substitute as Mourinho chose to introduce Scott McTominay ahead of the France international.
"He has to play with the same mentality as the team is playing," Mourinho explained.
In a separate interview, Mourinho said: "When the players give everything, the feeling is still positive. When you give everything for the club, you are a better team."
He amplified on that sense of togetherness at his post-match press conference.
"I mean together on the pitch in the sense of a compact unit," Mourinho said. "Sometimes you have teams that are positionally good and ready to press and with a desire to press, and I think these two boys [Nemanja] Matic and [Ander] Herrera, really strong mentality, is the way they play football, is to play at the top of their level and then the people in front of them were good also in that.
"[Marcus] Rashford is normal because of the way he always play but Romelu performance improved a lot in relation to previous matches, not because of the goal, but the way he was pressing, the way he was fighting for the team."