NICOSIA, Cyprus (AP) _ Iran's spiritual leader, Ayatollah Ali Khamenei, said today that Iran will never hold talks with the United States. Hours earlier, Iran renewed an offer to help free Western hostages in Lebanon.

The official Islamic Republic News Agency, monitored in Nicosia, reported in a commentary late Sunday that Tehran was ''ready to use its maximum influence for the release of all hostages'' if the United States freed Iranian assets worth billions of dollars it froze 10 years ago.

But Tehran Radio, also monitored in Cyprus, quoted Khamenei today as saying no Iranian leader will negotiate with the United States.

''Next to the usurper regime ruling over occupied Palestine, you are the most cursed government in the eyes of the Iranian people. No one in the Islamic republic will hold talks with you,'' the radio quoted Khamenei as telling U.S. leaders.

Khamenei has been seen as a so-called moderate in Iran, interested in restoring the country's ties with the West. His comments underlined the divisions in Tehran over whether Iran should help free the Western hostages in Lebanon.

''In Lebanon, America commits the greatest atrocities and encourages its puppet Israel in kidnapping and hostage-taking,'' Khamenei said, referring to Israel's abduction July 28 of Sheik Abdul Karim Obeid, a Shiite Moslem clergyman.

Khamenei did not specifically mention the Westerners held hostage. Most are held by pro-Iranian Shiite Moslem fundamentalists.

Khamenei was elected Iran's religious leader to succeed Ayatollah Ruhollah Khomeini, who died June 3. At that time, he was clearly allied with Parliament Speaker Hashemi Rafsanjani, the leader of Tehran's so-called pragmatists who favor rebuilding bridges with the West.

Rafsanjani, who was elected Iran's president, has made clear in recent days that dialogue with the United States on freeing the hostages is possible. He was behind the clandestine arms-for-hostages deal with the United States in 1985-86, during which three American hostages were freed.

But Rafsanjani's radical rivals in Tehran, led by Interior Minister Ali Akbar Mohtashemi, have said they oppose any dealings with the United States.

U.S. and Western intelligence officials have said Mohtashemi was closely linked with the formation of Hezbollah, the radical group believed to be the umbrella for factions holding foreign hostages.

The IRNA commentary Sunday said the United States must pressure Israel to free Obeid and secure the release of three Iranians missing in Lebanon since 1982 and all ''Lebanese captives held by Israel.''

The Israelis said they kidnapped Obeid to arrange a swap with three Israeli servicemen held in Lebanon. They later widened the offer to include the release of Western hostages.

Hezbollah has ruled out any exchange of the Israeli prisoners until Obeid is released.

The Sunday Times of London reported Sunday that Israeli investigators who have questioned Obeid believe two of the Israeli soldiers are dead.

Israel's chief army spokesman, Brig. Gen. Ephraim Lapid, said he refuses to accept that.

''My consideration is that they are alive and we must do our utmost to bring them home,'' Lapid told a news conference Sunday.

'We consider our prisoners of war ... as living until positive evidence proves the contrary,'' Lapid said.

The Sunday Times quoted unidentified senior Israeli government sources as saying Obeid's interrogators believe two Israeli infantrymen, Yousef Fink and Rahamim Alsheik, died of wounds within hours after their car was ambushed in south Lebanon in February 1986.

The hostages in Lebanon include eight Americans. The hostage held longest is Terry Anderson, chief Middle East correspondent for The Associated Press. He was kidnapped March 16, 1985.

The IRNA commentary Sunday said ''the hostages are not held by Iran'' but by ''unknown and underground groups.''

It said that ''the influence Iran has on these groups is merely spiritual, which in certain cases in the past has proved effective.''