The two clubs have agreed a deal for a January transfer, but the Dutchman has yet to give the Turkish outfit a response.
"Some people said that I would be in Istanbul today? The pressure being put on me is annoying," the midfielder told the Gazzetta dello Sport.
"Look, like all of the players who need to decide where to go this month, I have until January 31. I'm in no rush and I don't want to be rushed.
"After all that has happened in the last few months, in the context that I along with my teammates made football history here, I don't want to hear pressure being put on me.
"My doubts do not have anything to do with the offers that I have received," he continued.
"It's just that after all that I have done I don't want to feel the way I do, almost forced to make an important life decision in a short space of time. It's got nothing to do with money."