Pardew's men ultimately lost 3-1 at Old Trafford following two goals from Wayne Rooney and a Robin van Persie header, but things could have been much different after an incident in the 14th minute.
While attempting to collect a lofted pass, Yoan Gouffran found himself tripped inside the United area by Juan Mata, denying what Pardew felt was a clear goal-scoring opportunity.
Yet referee Mike Jones opted against awarding a penalty and, although Newcastle did later score from the spot through Papiss Cisse in the 87th minute, Pardew was left wondering what might have been.
He told reporters: "I thought we started the game well and the referee has made a bad call early, because I think that is a penalty.
"It's a goal-scoring opportunity, so you have to say that was clumsy and a penalty. I was disappointed with that.
"But the cutting edge was the difference between the two teams – they were really good going forward and when we over-committed they were clinical."
In response to the defeat, Pardew was adamant that no individuals would be singled out for criticism and, in fact, the manager seemed upbeat as he praised Spanish striker Ayoze Perez.
"I'm not going to criticise any of my players as individuals," he added. "This is a tough place to come, we know that.
"I think some of the performances from our players were outstanding, particularly Perez.
"The more he plays the more he engrains himself into the fabric of the team. [But] I think we need to defend better today – I think that is where we came unstuck."
