Ferdinand is being pushed by manager Sir Alex Ferguson for the Euros.
Keown told the Daily Mail: "I think Rio might be better retiring from international football with the problems he's had with his back just to extend his playing career.
"He will want to play. He won't retire because his future at Manchester United isn't really assured either. He didn't get words of comfort from his own manager who questioned his pace earlier this season, which was extraordinary.
"Rio's a big character who's done pretty well and you may want that in your squad."