The striker appeared to accidently handle the ball on its way into the net seven minutes from time after getting on the end of Shane Ferguson's cross.
"I think Demba just got a touch with his head and then it has hit his arm," Pardew told Sky Sports News.
"Unfortunately the defender and the goalkeeper have got no chance, but if you put a quality ball in like that, you are going to get a reward. It was a bit fortunate but we will take that."
The point has edged Newcastle up to ninth in the Premier League table.