The Argentinian has joined Norwich until the end of the season, having lost his place after five years as a regular at St James' Park.
He has made just two appearances this season and admits he is at a loss as to why he has been left out by Pardew.
"The manager told me in December I was not going to play any more and told me to find myself another club," he told several national newspapers.
"I don't know why it happened and I still don't understand what I did wrong.
"There were no rows with Alan Pardew or anything like that. He just said I needed to leave and that was that.
"I honestly don't know why I wasn't playing, you will have to ask the manager that.
"He just made his decision and that was it. Something must have happened - but I don't know what."