"I apologise to everyone. I made a mistake and I regret this mistake. It was my fault," said the Argentinian international.
"I am not a dirty player, I do not make a habit of showing disrespect towards referees, I don't like this and I can only think the high intensity of the fixture, against Manchester United, affected my behaviour that day. It was out of character, but I do not use that as an excuse.
"It is a bad thing when you let down your team-mates and leave them to play with 10 men, especially against Manchester United.
"They have been supportive and so have the Liverpool fans, but it didn't take away the pain. Looking back at that game, I was wrong to approach the referee. I approached him to talk to him, but I understand this was not a good idea.
"I reacted badly to the red card because I could not believe what was happening to me.
"I must learn my lesson, but move on from this and forget what has happened. I hope people know that I try to be fair and that I have no intention to be aggressive.
"I have to concentrate on the matches I can play in and stay focused on the Champions League. We have enjoyed a very good result against Arsenal and I am very much looking forward to the second leg.
"It is time for me to move forward, but not to forget the lessons from the past and the match at Manchester United.
"Off the field it has been a difficult time for me. My disciplinary record has been good until now, but I have to show that again. I always try to respect decisions by the referee and this is important."