The club's record signing has impressed in spells since his £37.1m arrival from Chelsea last month but results have not improved and there was more frustration on Sunday when they were held to a 2-2 draw by struggling Fulham at Old Trafford.
That result left United nine points adrift of the UEFA Champions League places and boss David Moyes admitted the 'soft' mental state of some of his players was to blame for the late goal conceded to Darren Bent.
But Mata is preaching togetherness as the way for United to get out of their current travails, with the next chance of finding some form coming up against Arsenal on Wednesday.
"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," Mata said on his personal blog.
"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.
"It seems that luck is not on our side, but I don't like to give excuses.
"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.
"We have to get better and improve our shooting accuracy, because we got many times to the box and could have scored more than two goals.
"I'm sure we will make it, but there are less and less games to play so the sooner the better."