The former Liverpool man admits he was unhappy with the performance of the match official, but refutes suggestions he was guilty of any inappropriate behaviour
The Portugal international was given his marching orders for two bookable offences and made his feelings known towards the official in a heated discussion on the pitch.
But the former Chelsea playmaker has insisted he did not spit at Ozkahya, though he was disappointed with the performance of the referee.
"I was fouled by Yekta [Kurtulus], just in the same way I did to him, but the referee didn't even whistle for the foul on me and right after when I made the same tackle - I pulled his shirt - our opponent was awarded with a foul and I was shown the red card," he told NTV Sport.
"I don't find it fair and I think Halis Ozkahya made most of his decisions in Galatasaray's favour.
"In my professional career, including in the Premier League, where physical tackles are toughest, I haven't been given a red card until now.
"This angered me more and that led to an argument with the match official. But I certainly did not spit at him. I think I was shown a wrong red card."
The 29-year-old could be suspended for up to seven matches if he is found guilty of the allegations.
Meanwhile, full-back Gokhan Gonul has refuted claims he is disloyal after he was seen hugging Gala coach Fatih Terim after the Istanbul derby.
Fans of San Kanaryalar took to social media to slam the Turkey international, but he admitted that he felt let down by the supporters for doubting his love of the club.
"I've been playing for Fenerbahce for six years now and there's not a day I didn't put in 100 per cent," he told the Turkish Sporting Press.
"I resent everything being said about me. Some doubt my loyalty to my team, to Fenerbahce, and I just can't believe that."