Special to The New York Times

United Nations, N. Y., Oct. 31- Secretary General Dag Hannarskjold has informed Cuba that the United Nations cannot provide observers for Cuba’s Presidential election Monday, it was learned today.

The Secretary General wrote to Dr. Emilio Nunez-Portuondo, head of Cuba’s delegation, that there was insufficient time to make necessary arrangements. Dr. Nunez-Portuondo submitted the request Oct. 20 in reply to complaints by leaders of the Cuban Opposition that they could not expect a free election under President Fulgencio Batista.