CASABLANCA, Morocco -- U.S. Secretary of State Warren Christopher has rejected a suggestion by the top UN commander that NATO warplanes might attack Bosnian government forces waging a counterattack against Bosnian Serbs.


Even though the policy of keeping havens clear of conflict applies equally to the mostly Moslem army as well as to the Serbs "we don't see any occasion for it at the present time," Christopher said Monday.


The threat was raised by Lieutenant General Michael Rose, the UN commander, as the Moslems pressed their most successful offensive in 31 months of war.


A U.S. State Department spokeswoman, Christine Shelly, said Monday in Washington, "It's hard to imagine the U.S. participating in that kind of an action against Bosnian government forces when they clearly have been the overwhelming victim in the aggression by the Bosnian Serb forces."


Christopher, talking to reporters at a Middle East-North Africa economic summit meeting, also said the United States still considered the Bosnian Serbs the main aggressors in the war. And, he said, the Clinton administration would bring every pressure to bear to compel the Serbs to accept a proposed settlement.


The United States last Friday formally introduced in the Security Council its long-threatened resolution to lift the UN arms embargo so Bosnian Moslems, who are far less endowed militarily than the Serbs, can get access to more weapons.


The Moslems would be exempted from the 1991 UN arms embargo in six months' time unless the Bosnian Serbs by then accept an international peace plan, which would require them to relinquish about one-third of the territory they have captured. The resolution is believed to lack the nine votes required for passage through the 15-nation council. U.S. spokeswoman Shelly said the United States intends a vote in the first half of November, when it holds the rotating chairmanship of the council. U.S. Ambassador to the UN Madeleine Albright will be at the helm.


In Zagreb, the UN said Tuesday that Bosnian Croats have joined the week-long Moslem offensive against Serbs in the northwest.


UN peacekeepers said Tuesday a Moslem offensive in northwest Bosnia appeared to have been blunted as Serbs fought back, but a spokesman for Moslem forces said "things are going well to our advantage," Reuters reported.


The Yugoslav news agency BETA quoted the Bosnian Serb Army as saying it had recaptured territory lost to the Bosnian government's Fifth Corps during a week of fighting.


There were no independent reports from the fighting on Serb soil around the Moslem-held Bihac enclave since the Serbs refused to let UN military observers enter the area.


Christopher said any consideration of NATO attacking the Moslems to protect havens would be analyzed on a case-by-case basis. But, he added, "based on the facts, I don't see any early prospect of that."