Iniesta has been at Barca for the whole of his professional career and has made 305 appearances since being handed his debut in 2002.
The 29-year-old Spain international's current deal expires in 2015 but Rosell has now indicated that he is close to agreeing fresh terms.
"Iniesta is a key player for us," Rosell told TV3 programme Hat-Trick.
"It is likely that the next great news for Barcelona will be the renewal of Iniesta's contract."
Rosell also reflected on the appointment of Gerardo Martino as Barca's new coach this season after Tito Vilanova had to step down to continue his battle against cancer.
"[Vilanova's] relapse has been the worst news of my presidency," he said. "Hopefully he will win his battle, but life goes on.
"We had thought already about Tata Martino the first time Vilanova needed to undergo treatment last season.
"[Sporting director] (Andoni) Zubizarreta chose the new coach from three names. I put down on the table that Martino would be my tip, nothing more. I will not say who the other two were, I don't think that is right."