Messi still has four years to run on his current deal, but Barca are ready to reward the Argentine ace with a new improved contract.
The 25-year-old has established himself as the best player in the world since coming through the Barca ranks and he underlined his importance to the club with two late goals to help them come from behind to beat Spartak Moscow in the UEFA Champions League.
Rosell feels the Catalan giants have a responsibility to look after Messi's interests, although he admits talks have yet to be scheduled
"It finishes in 2016, but it would be irresponsible to not improve his contract," Rosell told Catalunya Radio.
"You have to think about such things. Right now there is nothing scheduled, but this is a machine that is constantly in motion and things can change at any moment."
Rosell added: "The coaching staff think about next Sunday, we look further down the line and take the more distant future into consideration.
"Work has to start now on the contract that will take effect from 2016."
Rosell also refused to get involved in the debate surrounding Real Madrid's problems amid reports of dressing room unrest at the Bernabeu.
"The day you become preoccupied by other teams' matters is the day you start to lose," continued Rosell. "We need to remain a close group and work as such."