The 2-1 result saw United bounced out of the Champions League.
Mourinho insists he needs more money to turn things around at Old Trafford.
"Everything, everything has to change," Mourinho reacted to his side's exit. "Everybody spends money, right? Not just us, right? It's a natural process, every team invests. It's not a change for the sake of changing.
"It's a natural process and we're not the only team that invests money, all clubs invest money in players.
"I told yesterday that it would be a disappointment if we would lose the match. I don't want to make a drama out of it, we don't have time for that, we have a match on Saturday.
"We have no time to be sad for more than 24 hours and that's football. That is not the end of the world."