NICOSIA, Cyprus--Syria has talked Iran into delaying its winter offensive against Iraq and ending attacks on Kuwait, Arab diplomatic sources said yesterday.

The Syrian initiative could mark a breakthrough in attempts to end the seven-year Iran-Iraq war, which has threatened to engulf other nations in the strategic, oil-rich region.

As Iran's main Arab friend and only significant ally, Syria is uniquely placed to mediate between Tehran and the Arab states, most of whom support Iraq.

There was no immediate confirmation from Tehran or other Arab capitals that Iran postponed its offensive. The sources, who spoke on condition of anonymity, gave no indication how long the 'Iranians might hold off unleashing a new push.

But there have been several indications that tension was easing in the gulf despite the apparent failure of a 6-month-old United Nations ceasefire effort.

Iran and Iraq have halted attacks on gulf shipping for nearly two weeks, Arab leaders have toned down their condemnation of Iran, and gulf-based Arab diplomats reported unspecified "favorable gestures" from Tehran recently.

U.S. Defense Secretary Frank Carlucci arrived in Saudi Arabia on the last stop of a tour to assess the U.S. naval presence in the gulf region.

U.S. warships began to escort 11 U.S.-flagged Kuwaiti tankers in July to protect them from attack by Iran, which considers Kuwait an ally of Iraq.

The Syrian initiative, launched last month at the urging of Saudi Arabia, was aimed at opening up a dialogue between Tehran and the Arab nations of the six-member Gulf Cooperation Council to find ways to end the conflict.

Iran is Persian, not Arab. It shares the Moslem religion with the Arabs, but it adheres to the minority Shiite sect that has been at odds with the predominant Sunni branch of Islam for 1300 years.

Gulf-based Arab diplomats and council officials said the Iranians have said they are willing to open a dialogue and hold back on their long-anticipated ground offensive.

Diplomatic sources in Damascus said Saudi Arabia and the other council states recently persuaded Iraq to curb its air strikes on Iranian tankers.

That action, and the Syrian initiative, led Iran to halt its retaliatory raids on neutral shipping, sources said. Both sides have attacked more than 400 vessels in the waterway since 1981.

The so-called "tanker war" has scaled down sharply since Dec. 26 after a record 36 vessels were hit in one month. Only one ship has been hit since then, and Iraq apparently attacked the 26,260-ton Maltese freighter Alga by mistake.

The Iranians have been massing troops in the southern sector of the war front for weeks and have vowed to unleash "punishing blows" again Iraq.