"Organizer" works for me.
Interested in Language
Is it right if we say "FIFA is the world cup ORGANIZER" or there is a more suitable word for organizer.
As this was taken from the FIFA Wikipedia entry it is reasonable to say it is the organiser - "Although FIFA does not control the rules of the game, it is responsible for both the organisation of tournaments ...".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.