Ribery has starred since his summer arrival from Bayern Munich.
Karembeu told TMW: "What he's doing at Fiorentina doesn't surprise me.
"We wanted him at Olympiacos (Karembeu is their sports director) but chose Fiorentina.
"Franck is a champion and will still make the difference in Italy."
He added: "In the meantime, Serie A has become attractive again, almost like when I was playing."