The Newcastle defender was sent off in Sunday's 1-1 draw at Anfield for a wild lunge at Luis Suarez, which Sky TV pundit Chris Coleman later claimed was a "coward's challenge".
He said: "For me it was not a red card, but that is up to the referee. My conscience is clear.
"I don't understand the attacks I have received after that tackle. During all my years in England I have seen harder tackles than that.
"I have never been a violent footballer but football is a contact sport and sometimes it's difficult to stop your actions. I did not want to hurt Suarez but to stop a dangerous play against my team.
"I will always defend the Newcastle shirt."