JIDDAH, Saudi Arabia (AP) _ The 46-nation Organization of Islamic Conference on Sunday condemned a Tunisian professor for writing a comic book version of the Koran, the Moslem holy book.

Hamid al-Gabid, secretary-general of the organization, described the French-language work by Youssef Seddik as ''sacrilegious'' and ''heresy.''

Seddik's ''Si Le Coran M'Etait Conte,'' or ''If The Koran Were Told To Me,'' was published in late December in Paris, where the author has lived since 1983. The book uses cartoons to illustrate verses from the Koran.

Seddik told The Associated Press in Paris earlier this month that his aim was simply to make the Koran more accessible to young people. He denied he violated the tenets of Islam.

His wife, Saida, said in Paris on Sunday that her husband was out of town and unaware of the latest criticism of the book, sold by Alef for $10. Earlier this month, a professor of Islamic studies in Kuwait also condemned the book.

Mrs. Seddik said her husband is ''completely flabbergasted'' by the reaction. ''The book is written by someone who believes in Islam and who did not seek in any way to commit heresy,'' she said. ''I don't understand why the Islamic leaders have focused with such bitterness on the comic books.''

The statement by the Organization of Islamic Conference said, ''The OIC strongly reproves and condemns this series of publications as well as the publicity accorded to it.''

The group, headquartered in Jiddah, urged all member states and Islamic organizations and associations to remain vigilant against such ''pernicious acts,'' which it charged were aimed at undermining the Islamic faith.

''By indulging in a sacrilegious act which breaches the authenticity of the Holy Koran, the author of these series of cartoons has committed an act of true heresy harmful to Islam and Moslems because it violates the sanctity of the Holy Book and the inviolability of what was revealed in it.''

Last year, the group condemned Salman Rushdie, the Indian-born British author, for writing the novel, ''The Satanic Verses,'' which the organization and many Moslems around the world considered blasphemous.

Rushdie went into hiding after Iran's Ayatollah Ruhollah Khomeini called for Rushdie's assassination, and Iranian clerics offered a multimillion dollar reward for anyone who carried out the order.

Tunisia's highest religious body, the Higher Islamic Council, condemned Seddik's book Jan. 16 and said it contained ''profane images that constitute ... heresy.'' It said the book should be banned.

Mohammed Faidallah, head of Islamic Jurisprudence at Kuwait University, said earlier this month that Seddik's book constituted a ''criminal act that ridicules the sanctity of the Holy Koran.'' He branded Seddik ''a new Salman Rushdie.''

The Organization of Islamic Conference promotes Islamic solidarity and cooperation in the Moslem world. Its members include Indonesia, Egypt, Iran, Saudi Arabia, Bangladesh and Malaysia.