Rangers defender Madjid Bougherra has apologised to referee Calum Murray for his behaviour during the fiery Old Firm clash last week.
Celtic secured a 1-0 victory over their rivals at Parkhead in the Scottish Cup but it was a game marred by chaotic scenes of red cards and fierce touchline rows.
Algerian stopper Bougherra, 28, reacted furiously after being sent off in injury time and attempted to prevent Murray showing his cards.
He believes his dismissal may have been an incorrect decision but Bougherra admits he was wrong to react the way he did.
"I just wanted to explain to the ref I felt the punishment was too harsh. I'm truly sorry if it appears I was too aggressive," he said in the Sunday Mail.
"I have tremendous respect for Mr Murray - he's a good ref. I have respect for all the officials in Scotland.
"The next time he takes charge of a Rangers game I will offer him my apologies to avoid any misunderstanding.
"I'm still convinced I wasn't guilty but I will do it to maintain the respectful relationship I have with the authorities here.
"He made some mistakes in the Celtic game but there is a special atmosphere in these matches.
"I was going flat out and lost my self-control. After seeing the highlights on TV I realised what I had actually done."
Rangers moved to within five points of Celtic with a win over St Mirren on Sunday as the race for the SPL title is set to go right down to the wire.