Mata insists United must not dwell on the Fulham performance.
"The way to carry on is to stick together, the team and the fans, learn from mistakes and be positive, and we will show the character this team has always had," the Spain international said.
"I was frustrated after the match, but we will give everything until the end of the season, because that's what (the fans) deserve.
"The results may be better or worse but I'm going to give everything I have to help the team in every game, trying to enjoy football as I've always done, in the good and the bad moments.
"There is something we can always count on: the team's passion and sacrifice.
"We did fight until the end, and that's what I felt on the pitch, but once again we can't give excuses."