The all-rounder will skip this summer's tournament due to "personal reasons" and admits that he must take some time to reconsider his priorities when his spell with the Kolkata Knight Riders in the Indian Premier League comes to an end.
Writing in the Times of India, Kallis revealed: "At my age and stage of career, there are many things to consider outside the game and off the field, and I need to plan and be organised in order to play my best cricket.
"I simply cannot go through the motions or take up a place in a squad unless it has my full attention. So it would have been unfair of me to accept a place in the Proteas squad for the Champions Trophy next month.
"I certainly have not given up my ambition of playing in the 2015 World Cup but, right now, my priority is to finish strongly for KKR and then take some time to reconsider my priorities and consolidate."
The 37-year-old has played 162 Tests and 321 ODIs for South Africa.