Negotiations over a new contract for the four-time Ballon d'Or winner are not currently planned but his employers are open to idea of discussing a bumper deal
Reports have suggested Messi, 26, who is under contract until the summer of 2018, is chasing an improved contract after seeing Neymar arrive at Camp Nou in a big-money deal in the summer.
At Real Madrid, Gareth Bale signed a lucrative contract as part of his world record £86 million move to the Santiago Bernabeu, while Cristiano Ronaldo penned a new five-year-deal with los Blancos to make him the game’s top-earner.
“We have not yet spoken to Messi about a new contract but the door to our office is always wide open,” Rosell told reporters.
“He has to be the best-paid player in the word because he is the best player on the planet.”
Rosell had also said last week: "At the moment there are no discussions but while I am president, I think it would be extremely difficult for Messi to leave the club, if not impossible."
The 49-year-old also discussed the extension of Andres Iniesta’s contract, which is set to be made official in a deal that will keep him in Catalonia for another four-and-a-half seasons.
Rosell continued: “I can confirm the renewal – it is a great Christmas present for everyone connected to Barcelona.
“The new contract will run until 2018, then year by year in accordance with his sporting performance.
“Staying top of La Liga is even harder than getting there. We have to battle against everyone and everything, because we are the best and we represent what we represent.”