Lebanon and its sometimes awkward Palestinian guests yesterday reeled under their most humiliating lesson about Israel's punitive power to date.

With Lebanese sovereignty violated - and the last scrap of Palestinian autonomy gravely challenged the often unwitting partners were reduced to hurried allies.

Syria, for example, promised to provide air defense support against Israeli aircraft.

Nothing was said about using Syrian planes against the Israeli air force which struck with impunity from Beirut suburbs to a wide arc along the Jewish state's 60-mile-long border with Lebanon.

No certain case of Syrian weapons being fired against the Israelis was noted despite the presence of a largely Syrian 30,000-man peacekeeping mission here.

A deputy foreign minister in Damascus called in accredited ambassadors and asked for their intervention to stop the "aggression and to take decisive measures insuring the withdrawal of Israeli troops" form Lebanon.

Theoretically, however, the Israeli reprisal raid should have triggered automatic aid for the guerrillas as part of a mutual defense pact that they signed last December with the Algerians, Libyans, Syrians and South Yemenis.

Syrian caution reflects fears of being sucked into a full-scale war with Israel at a time Damascus' armed forces are incapable of handling such a task.

Palestine Liberation Organization spokesman Abdel Mohsen Abu Maizar was reduced to speaking of "urgent consultations" among the five allies, but mentioned no concrete decisions.

Lebanese President Elias Sarkis called in American Ambassador Richard Parker, presumably as part of Washington's continuing role as go-between between Lebanon and Israel.

Sarkis said Israel itself was to blame for the anarchy in the south since "it was Israel which has continuously stood in the way of allowing the Syrian peacekeeping troops into southern Lebanon."

Preme Minister Selim Hoss echoed the line in saying Israel "is responsible more than any other country for the abnormal situation in southern Lebanon" by preventing the peacekeeping force from entering the south "to stabilize security and restore legal authority."

The best the Lebanese could hope for was that the Israelis had achieved most of their military objectives in the first day and that the attacks would cease.

The Israelis, through their rightwing Christian proteges, now apparently control a continuous swath of border area for the first time.

Only last September, Israel vetoed an elaborately worked out deal which would have removed the Palestinian guerrillas from a major part of the immeidate border area and put in Lebanese army units.