"There are moments in life that are stressful and depressing. This is definitely one of those moments," the Bayern Munich playmaker told the German tabloid Bild newspaper in an interview published on Friday.
But he added: "No, I'm not worried for my future or my career, neither in the national team nor with Bayern. I'm convinced I'll win back the trust of people who maybe doubt me at the moment."
Ribery, along with France team mate Karim Benzema, who was also placed under investigation, faces months of uncertainty.
They will have to wait for police to unravel a prostitution ring centred around a night club in Paris's Champs Elysees district, the first stage of a criminal investigation that can lead to charges.
The offence carries a maximum penalty of three years in prison and a 45,000 euro fine, although a conviction hinges on proving the accused knew the minor's age.
Ribery's lawyer said he did not know that the girl at the centre of the probe was under 18 at the time.
Ribery, who took part in a disastrous World Cup campaign in South Africa when France were knocked out in the first round, said it was hard for him to concentrate on football.
"At the moment, it's a bit difficult for me," he said.
"I hope that the discussions around my private problems and my injuries will soon come to an end.
"The most important thing for me is the football.
He added: "I must get past this low point. I'm a player who is very much in the public eye, about whom everything gets reported and who everyone knows. I must live with that."
Ribery thanked the Bundesliga champions for their support.
"The whole club has stood unconditionally behind me. That is something which will make me never forget Bayern Munich.
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