United’s boss was deeply disappointed with the criticism aimed at Morgan by some fans on Saturday.
The 28-year-old has divided opinion since arriving on loan from Chesterfield last month, mixing flashes of inspiration with body language which has at times provoked frustration on the terraces.
It reached a new level in the goalless draw with Gillingham, when Morgan was booed by a minority of supporters for sitting down in the second half shortly before being substituted.
After the game it became clear the actions were due to a minor groin injury, which forced him out of the game.
Morgan tweeted on Saturday evening: “So misunderstood!! Thanks for all the support!!”, although he has since been backed by many U’s supporters on Twitter in response.
The boos were not welcomed by Wilder, who exchanged words with some supporters behind the bench.
He said: “I didn’t like the Dean Morgan situation because he’s putting a shift in for the club and I said that.
“I had (first-team coach) Andy Melville telling me to calm down a little bit, but I don’t like that – he’s playing for the football club.
“He’s not a player that runs about and smashes into people, but he has the ability, he single-handedly got Aldershot in the play-offs two years ago and he was an excellent player for Chesterfield last year.
“There will be days when he’ll play like that, but I’ve got to make a decision.”
The U’s boss has been criticised in some quarters for naming a three-man forward line of loan players – Morgan, Cristian Montano and Scott Rendell – in preference to contracted players such as James Constable and Oli Johnson, who have been on the bench in recent games.
Wilder felt injuries and suspensions had forced his hand in recruiting the players and is happy with their contribution.
He said: “It’s absolute rubbish, what do I do, not play them?
“It’s not my fault players have got injured, I have to play loan players.
“I think (Morgan and Montano) are typical wingers, we’ve got players that I want them to come alive in the final third, I don’t want them in my defensive third.
“Sometimes they have to put a shift in, but I don’t want them tackling back, we gamble and leave the forwards out of it because when we win the ball we want three targets to go forward.
“Some people like Dean, some don’t, but when he’s getting abuse that’s really poor, I can’t do anything about those people.”