The France international is facing a spell on the sidelines after suffering a hamstring injury during the Red Devils' 3-0 win over Basel in the Champions League last Tuesday.
Mkhitaryan, who has scored once and produced five assists in the Premier League so far this season, believes that Pogba's absence will be felt.
"It's hard, because he's a top player for us," the Armenian told SFR Sport. "It's going to be very difficult, but the coach knows how to make up for that and we're going to help him come back stronger."
The former Juventus star scored two goals and two assists in four top-flight appearances.