Arsenal and the Red Devils have been linked with a £23m bid, but Martínez urged the giant midfielder to stick with the Toffees beyond the summer.
“Marouane is an international footballer and he’s going to be involved, if all goes well, in a World Cup next year,” Martínez told Everton’s website.
“He’s had a fantastic impact in the Premier League and hopefully now is the time he can carry on showing his massive influence in the game for us.
“He’s still a very young man but I am really looking forward to seeing Marouane working hard and making sure that he sets really good standards at this club. We have a very good group of senior players in our dressing room, and some players need that extra bit of responsibility.
“We have youngsters at the club and they need to get opportunities but the senior players at the club are massively important to start the season as strong as we can be.”