Chris Lines' 19th-minute strike was enough to separate the two sides and give the Pirates a vital three points.
Parry said: "It was awful. They beat us fair and square. They were the better team for big parts of the 90 minutes. They took the game to us and we couldn't handle it.
"My concern is how poorly we played to a man. Everyone struggled. We couldn't keep the ball and we couldn't pass the ball and they caused problems for us.
"We had a long discussion and things were said which will stay in the dressing room. Everyone is scratching their heads.
"The players were off form and couldn`t get close to their opponents. I hope it was just one of those days because I cannot accept that. I cannot blame the fans for their adverse reaction. Their criticism is fully justified."