The midfielder returned to the Sardinians on-loan from Inter Milan this season.
“We are satisfied," Giulini told Radio Anch'io Sport. “He is happy to be back in Cagliari and we're happy with his performances.
“He's a decisive leader in our matches and in the way he pulls the team forward."
On a permanent deal, Giulini continued: “We are not thinking about it now, the time to start talking will be in March or April, even if there's not much to talk about.
“He is an Inter player, of great value and has bounced back well. Unfortunately, I think we are doing Inter a favour. I think it will be difficult."