Deniz Naki, who played for the Ankara-based Turkish Super Lig side Genclerbirligi, said he was attacked by unknown individuals who left him with injuries to the face and hand.
Naki, who was born in Germany, said the men insulted his mixed Kurdish and Alevi origins and also threatened him over his vocal support for Kurds resisting Islamic State (IS) jihadists in the battle for the Syrian town of Kobane.
"My family is very worried about the incident and so as not to cause them any more worry, I have left Turkey to go to Germany," he wrote in a Turkish statement on his official Facebook page.
"My being here (in Turkey) no longer had any meaning," he said.
Naki, who adheres to the Alevi offshoot of Shiite Islam which is majority Sunni Turkey's biggest religious minority, had in recent weeks written several tweets hostile to IS.
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"I would like to make one thing clear: I am from Dersim and I am Alevi," he said, using the former name for the Kurdish-Alevi majority Tunceli province.
"I am proud of this and will continue to be proud of it," he added.
He criticised the club for its "insensitivity" over the incident and said the contract has been terminated as it "was not possible for me to stay in that environment".
In a German language statement, he went even further, saying: "The reason I am leaving is that I can no longer endure the fact you cannot play football neutrally in this country".
A midfielder, Naki, 25, represented Germany at U-19 level and also played for Hamburg-based top German side FC St. Pauli.
The battle for Kobane has caused deadly social tensions in Turkey, with over 30 people killed last month in pro-Kurdish protests against the government's policy on the crisis.