The Ukrainian joined the Bundesliga outfit in August following a spell on loan with the club.
However, he has struggled to find form in the early stages of the season and has lost his place in the starting lineup in recent weeks.
Voronin voiced his concern at his lack of playing time, saying: "It is up to the coach. I feel out of place with the team."
When asked about his future with the club, he responded: "That's also not my business. That's up to my agent."
Dusseldorf general manager Wolf Werner said that the 33-year-old needs to show more on the pitch.
"Of course, we hoped for more but sometimes you can't rush things," ESPN quotes him as saying.
"You really believe Voronin is pleased with his situation? He has to give an answer on the pitch now.
"I am confident he will do so. We have not doubts about him."
Voronin has started six games this season, while also appearing twice as a substitute.