Barnetta joined Schalke on a free transfer from Bayer Leverkusen last summer and he signed a three-year contract at the Veltins-Arena.
However, the Switzerland international was largely restricted to the role of substitute and started only two games in the Bundesliga.
He has a further two years left on his deal with Schalke, but does not want to experience another season of limited playing time.
"I am under contract with Schalke until 2015," the 28-year-old told Sport-BILD weekly.
"I have not been playing that regularly and, if I feel I will not have a greater chance of regular first-team appearances, I will have to discuss my future with the club. This is a fact."