With Juventus No1 Gigi Buffon injured, Marchetti is currently Italy's World Cup goalkeeper.
Cellino said: "Marchetti is our goalkeeper and it is an honor for us to have him as a player of Cagliari, and will not necessarily leave. He's a great goalkeeper and deserves a big stage, but Cagliari has no urgency to sell.
"Wait a week, then decide. I'll give his agent until June 30 to find an important offer, if not, he will remain with Cagliari."