DUBAI, UNITED ARAB EMIRATES, SEPT. 15 -- U.N. Secretary General Javier Perez de Cuellar ended four days of talks on the Iran-Iraq war today with Tehran and Baghdad showing no evident willingness to accept a cease-fire in their seven-year conflict as demanded in a resolution of the U.N. Security Council.

The apparent failure of the peace mission, according to diplomats and political observers in the Persian Gulf region, opens the possibility of a new round of intense fighting and a major test of superpower attitudes toward the conflict.

Shortly after Perez de Cuellar left Baghdad, an Iraqi military communique said Iraqi troops had pounded various Iranian positions on the battle front. Meanwhile, Kurdish guerrillas aligned with Iran said they launched a major offensive in northern Iraq, seizing territory close to an oil pipeline by which Iraq exports oil through Turkey.

With the approaching end of the brutal heat of summer, analysts now are looking for signs that Iran is preparing to resume its large-scale ground attacks against Iraq as well.

Diplomats noted that Iraq instigated much of the latest round of fighting while Iran appeared content with the extended lull that preceded the latest hostilities. In effect, according to diplomats, Iran was honoring a cease-fire but could not be seen to be acceding publicly to U.N. demands.

"The Iranians need a break to refill their coffers," said one Asian diplomat. "There are signs they are hurting and that they welcome the break in attacks on shipping so they could get their oil out of the gulf unhindered. Their {foreign currency} reserves seem to be down and the value of their currency took a sudden drop of almost 50 percent on the black market recently."

A U.N. official with Perez de Cuellar said in Baghdad today that Iran's position had changed slightly. "At least you could mention things you could not even have discussed a year ago, such as a cease-fire," he said. Yet, as a western diplomat sympathetic to the mission noted, the government in Iran is so fragmented that Perez de Cuellar could not even meet with the top Iranian leaders at one sitting, but had to deal with them separately.

{Perez de Cuellar, who arrived in Paris Tuesday en route to New York, said he had received "very clear responses" during the sessions, but declined to elaborate, Reuter news agency reported.}

Iraq, which sends its oil to market via pipelines, primarily through Turkey, seemed unwilling to let Iran benefit from the let-up in attacks on shipping and revived the large-scale tanker war.

Iraq's decision to resume attacks on tankers underscored an irony of the latest phase in the war: Iran became a primary beneficiary of the U.S.-led drive to protect navigation in the gulf with foreign escorts, even though such protection ostensibly was provided for Kuwaiti tankers.

Diplomatically, pressure is expected to build at the United Nations for imposition of sanctions in the form of an arms embargo against Iran for not accepting the Security Council cease-fire demand.

Iraq has said it would accept the measure, but only in its present complete form and only if Iran does. Iran has demanded that Iraq first be labeled the aggressor in the war before it will consider the cease-fire and other points in the Security Council resolution.

In addition to the cease-fire, the resolution mandates a return of forces to recognized international boundaries and an exchange of prisoners. It calls for an impartial commission to establish responsibility for starting the war, but only as a subsidiary element.

China, one of the five permanent members of the Security Council and reportedly a source of arms for Iran, appears ready to support an arms embargo to try to end the conflict, according to western diplomats.

Britain, France and the United States also are believed to favor clamping an arms embargo on Tehran, leaving uncertain only the position of the Soviet Union.

Western diplomats in the gulf say Moscow may go along, but also may try delaying tactics, such as linking the arms embargo to a withdrawal of western fleets from the region, as part of its continuing efforts to bolster relations with Tehran. The Soviet Union is a major arms supplier to Iraq.

Perez de Cuellar plans to report to the Security Council on his mission this week. Deliberations on a possible embargo are expected to begin immediately, unless council members decide to wait to see what Iranian President Ali Khamenei says when he arrives for the General Assembly session, which opens this week.

With the exception of artillery attacks and some ground exchanges, the war front has been relatively quiet since Friday night, when Perez de Cuellar began his mission in Tehran, and there have been no attacks against shipping in the gulf. Shipping sources say traffic in the Strait of Hormuz has been unusually heavy as vessels try to take advantage of the lull in attacks.

With an increasing number of warships from the United States and European nations operating in gulf waters, diplomats in the region fear that the conflict could expand by accident.

"The danger lies in someone making a mistake," said one western diplomat. "Contact between the navies is not a problem. But what might happen in an air attack? It seems the Iraqis are not identifying themselves."

There were reports from Rome late today that an eight-vessel Italian flotilla had left for minesweeping duties in the gulf, adding to the ships of the United States, Britain, France, the Netherlands and Belgium already here or due to arrive shortly.

The Soviet Union also has ships in the gulf.