Poortvliet believes the first goal scored by Danny Welbeck should have been disallowed and was also seething at the straight red card issued to youngster Matt Paterson.
"It was offside," he said of the opening goal.
"The referee's assistant should see it because he is on the same line as the player.
"I know the boy very well, it was a normal tackle," Poortvliet said in regards to the red card.
"I was disappointed in the game by the decisions.
"The boy made a tackle on the ball with one foot. He hit the ball but he sent him off, and that was wrong.
"I only feel sorry that after the red card it was not a real game any more. It was a pity for the people and for my players because I think they deserved more than that."