"If you feel pressure, stay at home. When I say home, I don't mean the stadium, I mean home, home and watch on TV. If you feel pressure to play where the people come to support, come on. I never feel pressure to play at home," he said.
The United manager spoke of his frustrations with his team's sub-par performances before the match against Swiss side Young Boys, saying he wanted his players "not to be reactive but proactive".
"I want the team to start strong, I want the team to have a go immediately and it is a bit frustrating," he said.
Mourinho said defender Victor Lindelof would likely be out of action for "quite a while" with an injury.
"(Lindelof) does the scan (Tuesday) but, by the experience of the medical department and the feelings of the player, he has a muscular problem and a muscular problem takes time," he added.
"I would say if we have him for the Christmas period -- where we need, if possible, every player to be available for that difficult period until the Newcastle match on January 2 -- if we can have Victor available for that period, it will be good."
Manchester United will go against Youngs boys on November 27. United stands at the second position in Group H on League table whereas Young Boys are places at last with just one point.
'If you feel pressure, stay at home. When I say home, I don't mean the stadium, I mean home, home and watch on TV,' said Mourinho.