UNITED NATIONS, AUG. 20 -- The 15 members of the U.N. Security Council today called on Secretary General Javier Perez de Cuellar to pursue his effort to get Iran to comply with a council resolution demanding an immediate cease-fire in the seven-year war between Iran and Iraq.

The council's instructions made it clear that the belligerents must deal with the resolution in its entirety. Diplomats said this means Iran may not accept only the parts of the resolution it likes while failing to comply with the cease-fire demand.

Iraq has agreed to accept the entire July 20 resolution, but the Iranians have suggested that some elements, such as creation of a commission to determine who started the war, must precede a cease-fire.

The council's instructions to Perez de Cuellar were framed by the council's five permanent members -- the United States, the Soviet Union, China, Britain and France.

Perez de Cuellar asked the council for guidance a week ago after Iran made it clear that it would not accept the resolution as a basis for reducing the level of hostilities.

Subsequently, Iranian Foreign Minister Ali Akbar Velayati orally invited Perez de Cuellar to visit Tehran to discuss security in the Persian Gulf region, but the secretary general asked for a written invitation specifying that Iran is willing to discuss a cease-fire.

In Rome, Vernon Walters, the U.S. ambassador to the United Nations, was quoted in an Italian newspaper interview as saying Iran is playing for time.

Velayati's deputy, Mohammed Larijani, is due in New York this weekend and is scheduled to meet Perez de Cuellar Monday.

Western diplomats said the Iranians seek to string out their talks with the United Nations without making a commitment to end the fighting, in order to avert a second council resolution calling for a global ban on the sale of arms to Iran.