The Bluebirds player was involved in both games for Iceland over the break, a decision that did not leave Warnock very happy.
It appears there was some confusion about how much Gunnarsson was expected to play in those games.
"Originally I was told they weren't going to play Aron on the plastic pitch for the first game [against Andorra]; he played for over an hour," said Warnock in his press conference.
"And then he plays against France for 93 minutes. I can't understand that at all really.
"I know it's a new manager (Erik Hamren took charge after last year's World Cup), you want to do well, but when you're 3-0 down with 80 minutes gone, surely you can substitute a player.
"I bent over backwards for Iceland last season to allow him to go to the World Cup, gave him a new contract, and he had three months this season where he was out. We had to build him back up.
"I was disappointed with the Iceland manager. I'll be speaking to him later today (Friday) as well.
"I think that was pure selfishness and am so disappointed in Iceland for doing that."