United beat Young Boys 3-0 in their Champions League Group H match on Wednesday and while upbeat about his team's performance the Portuguese manager took aim at the pitch.
"Now I can say, I don’t understand how you can play the best club competition on artificial pitch," said Mourinho, who had declined to comment on the surface before the game.
"You know, probably some fear injuries. I had some players after training yesterday – light training – and they were feeling ankles, back pains, sore.
"It’s not easy, especially not for people who are not adapted to it. Also a little bit of a fear in the duels.
"People are used to great surfaces in England, always watered if not rain – the clubs they provide the water and the football is much more beautiful that way," Mourinho said.
Before the game, Mourinho had urged his team to follow the example of Swiss tennis great Roger Federer and show they were capable of winning on different surfaces.
Italian champions Juventus and Spain’s Valencia will also visit Bern in Group H.
(Reporting by Simon Evans, editing by Ed Osmond)
