Jesse Jackson, insisting he has not sought direct talks on the release of American hostages, says he merely wanted to appeal for their freedom as the Iran-Iraq war nears a possible end.

Iran promptly rejected Jackson's effort, and the Reagan administration said Thursday the matter should be left to "official channels." Democratic presidential nominee Michael Dukakis, Jackson's opponent in the primary elections, said private citizens should not try to conduct foreign policy.Yet amid all the commotion, U.N. Secretary General Javier Perez de Cuellar, at Jackson's request, appealed to Iranian Foreign Minister Ali Akbar Velayati to help gain the "unconditional release" of the American hostages.

"The captives should be released on moral and humanitarian grounds as an act of good faith," Jackson said in a statement. "There should be no linkage (to other goals) in their release."

Citing a possible end to the Iran-Iraq war, the Chicago civil rights leader said in a telephone interview, "This is certainly a good time to seize the moral initiative and appeal for their release."

Jackson's office denied reports that he sought, through intermediaries, a meeting with Velayati to open talks. It insisted he only made an appeal through Perez de Cuellar for the hostages' freedom.

An unidentified Iranian official said Velayati has no intentions of discussing the matter with Jackson or even addressing any issue other than the war.

Dukakis, on the campaign trail in Cleveland, indicated he was not fully aware of Jackson's initiative, but the Massachusetts governor remarked, "As a general rule, private citizens should not try to conduct foreign policy."

Frank Watkins, Jackson's political director, said the preacher-politician was merely making a "private moral appeal. He isn't trying to conduct foreign policy."

The State Department reiterated the administration's position that the "best chance" for release of the hostages is through official channels.

Nine Americans are being held hostage in Lebanon to captors influenced by Iran. Two, reporter Terry Anderson and university dean Thomas Sutherland, have been missing for more than three years. Nine other Westerners, including Briton Terry Waite, are also believed being held.

Iran, meanwhile, reported major victories on the central war front on Friday.

A military communique read on Tehran Radio said Iranian troops backed by jets and helicopters drove Iraqi soldiers and Iranian dissidents from three towns in western Iran and were advancing toward a fourth. It said Iranian forces had killed 4,500 Iraqis.

At the United Nations, Iraq representatives had no comment on the Iran report.