The young Bosnia international revealed contact with United last week.
And he told Dnevni Avaz last night: "It is true that both the club and I have an official offer from Manchester United, but at this point I would not like to talk much about this.
"My agent knows everything about this proposal from England and together we will study it and then make a decision.
"I'll take my time, no rush. I have to seriously think about an offer like that and of course the board of Schalke also have to think about it."