The former Sheffield Wednesday boss saw the Iron lose for the fourth time in five league games, leaving them mired in relegation trouble.
He said: "I'm disappointed but I don't think we can argue about the result because Sheffield United punished us for the mistakes we made. Particularly the first goal, which was our own undoing.
"You can't give a team who are at the top of the table and in fine form opportunities like that. That put us on the back foot.
"I have to say that in the first-half, I thought we were the better side. With the opportunities that we had, we should have come in at least on level terms. Damien (Mozika) missed a clear sitter from six yards.
"I thought we were trying so hard to get a goal back. It showed the mentality of the players that it wasn't going to affect them.
"We should have got a reward for out first-half performance but we didn't. Once that second goal went in we had to change and we left ourselves open after trying to change the game.
"It was quite an aerial battle against a very big side in Sheffield United. We took some knocks and bruises but we certainly didn't crumble because of it."
- Sports & Recreation
- Sheffield United