Boateng was linked with Manchester United in the past month, while Paris Saint-Germain coach Thomas Tuchel is believed to be keen on the defender.
However, Robben is hopeful the club will keep the German centre-back for the upcoming season.
"For me Jerome is one of the best central defenders in the world," the Dutch winger said, according to FourFourTwo.
"We've had success with him a lot in the past and I know him very well.
"Jerome is simply very important for this team. But we have enough competence in the leadership for the decision."