Laws was frustrated that the referee Kevin Wright failed to notice what he considered a foul by Iwelumo on defender Richard Hinds before the decisive goal.
He said: “I'm gutted and very disappointed. In my eyes it's very difficult to play against 12 men.
“The referee never gave us anything, we all saw the push and he gave us nothing. I got sent upstairs out of the dug-out, but he needs to have a look at his own performance.”
Laws was told by U's boss Phil Parkinson that his team was one of the toughest his side has played of late but for the Iron boss that was little consolation.
He did, however, draw some joy from the way his side performed, adding: “I will take a lot away from the game we did exceptionally well but got nothing from it.
“We are playing well at the moment and if we can keep that up I'm very confident that we will be able to consolidate our position in the league and build on it.”
Colchester United boss Phil Parkinson insisted he saw nothing wrong with the challenge that Iwelumo madeon Hinds
He said: “I really didn't see a lot in it, I'll have to have a look at the tape.
“Brian Laws will be very disappointed as their team played very well.
“They pushed hard throughout the game and we had to have 75 minutes of real gritty determined football to keep ourselves in it.
“Aidan Davison, our goalkeeper, was influential at the back keeping a very young defence calm and focused."