"Whenever there is a game, a lot of people come together and we want to discourage gathering at this point," said Hassan Bility, president of the Liberian federation.
The Liberian group also asked FIFA to reschedule visits by top officials, including one by President Sepp Blatter, that were planned for August and September.
Sierra Leone led the two-leg series 2-0 after winning in Freetown two weeks ago. It advances to the final group stage in qualifying for the African Cup next year in Morocco. The African confederation said it accepted Seychelles' withdrawal but would investigate the reasons.