Campbell insists Ferdinand did not snub England coach Roy Hodgson after pulling out of the squad last week.
He said: "Rio has not snubbed the England manager.
"He said he would love to be involved in the next game. It's just a crucial moment for both England and his club Manchester United, so it's difficult for him to decide.
"It's physical, international football, and the travelling is demanding. Can Rio play for England again? People need to talk and work it out."