An explosion of shellfire has complicated President Reagan's apparent bid for a face-saving redeployment of Marines from Beirut, and Lebanese Druze leaders warned of ''revenge'' against remaining American ''diplomats, civilians, and interests'' in the city.
Druze leader Walid Jumblatt maintained that the new outbreak of violence had come even as he and Syrian leaders were weighing ways of bringing a United Nations force to Beirut to facilitate an orderly and ''honorable'' pullout of the Marines and their West European partners in Beirut's multinational force.
Diplomats here said Mr. Jumblatt is also understood to have received a message recently on the subject from the Soviet Union, which could veto any such UN move from its seat in the Security Council.
There was no word on the contents of the note - said to have come from Soviet Foreign Minister Andrei Gromyko after he had been queried on the UN option by European foreign ministers at the European security conference in Stockholm last month.
Earlier Wednesday, the Syrians and their Soviet allies announced that Kremlin Politburo member Geidar Aliyev would arrive here within the next week for talks with Syrian leaders. Mr. Aliyev will be the highest level Kremlin visitor here since Israel's 1982 invasion of Lebanon.
Tuesday night, Mr. Reagan said he was ordering the Marines redeployed to vessels offshore. He coupled this with a vow to unleash naval and air strikes against further fire on Beirut ''from parts of Lebanon controlled by Syria.''
But on Wednesday fresh shell exchanges erupted between Maronite Christian east Beirut and Druze positions in the hills above the capital - an area to which troops of the Syrians' 40,000-man force in Lebanon have free access. The US battleship New Jersey then boomed dozens of shells onto the Druze areas.