Luciano Becchio's sixth penalty of the season settled a poor-quality contest but Freedman thought an Alan Tate tackle on David Ngog late on should have yielded a spot-kick for his side.
Freedman said: "The referees and their assistants are part-time, so it is not their fault. They don't train all week and they don't get help. They don't get coached or mentored.
"There should be a more professional approach because there is so much at stake.
"It was a game we should have won because we created most of the chances. Our game plan is working but our defence is letting us down and that is what happened today.
"We looked comfortable and in control for most of the match but Leeds never gave up and I am sure their manager is very happy with the win."
Neil Warnock dismisses his counterpart's penalty claim, saying: "It was a blatant attempt to win a penalty out of nothing. It was clutching at straws."