The 32-year-old was left out of both the Europa League and domestic lists, which means he will not be available until at least January and has likely played his last match for the club.
"This is a difficult message to write to Arsenal fans that I've played for over the past few years," he wrote. "I'm really disappointed by the fact that I have not been registered for the Premier League season for the time being.
"Upon signing my new contract in 2018, I pledged my loyalty and allegiance to the club that I love, Arsenal, and it saddens me that this has not been reciprocated.
"As I have just found out, loyalty is hard to come by nowadays. I've always tried to remain positive from week to week that there's maybe a chance to get back in the squad soon again. That's why I kept silent so far.
"Before the coronavirus break I was really happy with the development under our new coach Mikel Arteta -- we've been on a positive way and I would say my performances were on a really good level.
"But then things changed, and, and I was not longer allowed to play football for Arsenal.
"What else can I say? London still feels like home, I still have many good friends in this team, and I still feel a strong connection with the fans of this club.
"No matter what, I will keep fighting for my chance and not let my eighth season at Arsenal end like this.
"I can promise you that this hard decision won't change anything in the my mindset -- I will continue to train as best as I can and wherever possible use my voice against inhumanity and for justice."
Ozil joined from Real Madrid in 2013 and has scored 44 goals in 254 appearances for the north London side.