The Argentina international is currently holding talks with West Ham over a contract extension.
"Manu's a young player, he's important, and he's committed to this club," Pellegrini said. "He's happy here. I think it's an honour in every club to have players in your squad that are nominated for their international squad. They must play always for their country, it's an honour for the club.
"I hope that Manu and all the players that will be nominated will come back here and, if they have one day more to recover, even better."