The Swiss side are widely tipped to lose the forward over the course of the summer transfer window, with Gnonto a senior Italy international and firmly in demand.
Just 18 years old, Gnonto made 35 appearances for Zurich last season and grabbed ten goals as the side eased to the Swiss Super League title.
Feyenoord have been linked with wanting Gnonto, while it has also been claimed that Leeds have opened talks about signing him this summer.
Zurich sporting director Jurendic admits he would not be surprised to see a bid come in and stressed the club must be ready to react.
“If the big leagues make the big transfers, it will have an effect on the bottom”, he told Swiss daily Blick.
“For us it is simply important that we are prepared.”
Zurich are only prepared to let Gnonto move on if a bid over €10m is lodged, with talk that an offer of €4m could land him quickly dismissed.