Hitzlsperger, who won 52 caps for his country and also played over 100 games for Stuttgart, was released by Everton at the end of last season after a short stint at Goodison Park.
He told the Suddeutschen Zeitung: "I've been sure about it for a few days: I won't be playing anymore."
According to Hitzlsperger, his body was giving the "appropriate signals" that it was time to stop.
"I think it's enough," he said.
Although he continued to receive offers to resume his playing career, the newspaper reported, Hitzlsperger said: "I've noticed: I need something else."
It was the strain of "many transfers and some injuries" that tipped the balance, said the player who joined Villa as a teenager in 2000 after starting his career in the Bayern Munich youth ranks.
He moved to Stuttgart in 2005, before having spells at Lazio, West Ham and Wolfsburg, with Everton his last stop.