Mourinho’s side were unable to bounce back after a controversial VAR decision denied them a first half equaliser.
Tottenham were outfought by the Blades after that and their hopes of qualifying for the Champions League are in tatters.
Mourinho was especially disturbed by the way Tottenham’s stars lacked the desire to fight back from the VAR blow.
“There was a lot in the game, there was a possibility of shortening distances to Champions League positions, there was the possibility of being more stable for the Europa League positions fight,” Mourinho told reporters on Saturday.
“I believed in the evolution of the team and I thought that by a desire point of view, they put more in than us. That’s something that disturbs me.
“It’s something that I feel, I don’t know, that’s my way of being – it’s something that destroys me a little bit on the inside because I think the last thing in football is when you have the feeling you could, you should do more.
“I always say it’s not a problem for me to lose because my opponent is better.
“It’s not a problem for me to lose because my goalkeeper made a big mistake, it’s not a problem for me to lose because my striker missed two chances with an open goal or a guy missed a penalty in the last minute.
“It’s not a problem for me to cope with mistakes and defeats. It’s a problem when my feeling was we could do much more.”
Tottenham have a chance to resurrect their Europa League hopes against Everton on Monday, although England midfielder Dele Alli is a doubt after picking up a hamstring injury on Saturday.
“Something today in training with Dele Alli,” Mourinho said. “When I say something it’s because I don’t think it’s big and I don’t really know what it is.
