Lebanon's tenuous cease-fire generally held today, although several people were injured during isolated incidents of fighting.

The announcement of a truce yesterday led to an exuberant mood here. Streets were clogged today with pedestrians and motorists on both the Christian east and Moslem west sides of town for the first time since the outbreak of civil uprisings a month ago.

Yet there was also a deep apprehension among residents here that the house of cards assembled by U.S. and Saudi mediators to achieve a truce might soon topple.

In the Shiite Moslem slums on the southern edges of the capital, tense militiamen still had their guns and checkpoints only yards away from the guns and checkpoints of the Lebanese Army. Druze fighters and Army soldiers faced one another warily from dug-in positions in the mountains overlooking the capital. They clashed there in a 90-minute firefight after the 6 a.m. cease-fire went into effect.

The agreement to stop the fighting came although no arrangement had been made to send international observers to the trouble spots to monitor the cease-fire. U.S. officials said they expected more violations of the cease-fire but hoped that international observers and a "security committee" of representatives from the Army and the militias could soon be formed to quell incidents quickly.

State-run Beirut radio reported that after the cease-fire, the Army wounded one of three gunmen who tried to approach its lines near the hill town of Suq al Gharb. It said soldiers also wounded a second gunman when they came under sniper fire in the Shiite Moslem district of Shiyah, Reuter reported.

[Army sources told The Associated Press that two soldiers were killed by Druze snipers at Kaifoun, about a mile from Suq al Gharb.]

Lebanese Prime Minister Shafiq Wazzan offered his Cabinet's resignation today, opening the door for the formation of a "national unity" government that would include representatives of Lebanon's many warring factions.

Although Lebanese President Amin Gemayel asked Wazzan to delay the resignations, the gesture was regarded as a hopeful sign. But there was scant illusion here that the the troubles of a country involved in eight years of a complex civil war involving the major Middle East and western powers would be easily resolved.

"It's going to be hard" to complete the peace process, said a senior U.S. official who briefed western journalists this morning. "It's going to take some time for them to accept the realities and alternatives. It will take a lot of shouting and trading and perhaps violence."

He also said that as "the situation on the ground" changes, the U.S. Marines could move out of Beirut into other areas, including the troubled Chouf mountains, if the Lebanese government requested it. Gemayel's government so far has not asked for such a broadened role, he added.

Those most bitter today were the leaders of the long-ruling Maronite Catholic establishment who had been gleeful only a week ago when U.S. warships fired their big guns to rescue the Lebanese Army and Gemayel's government from defeat by Syria and the Damascus government's Lebanese Druze allies.

The Maronites' dismay came because the sketchy cease-fire agreement--concluded after strong pressures by the Americans and Saudis during the weekend--gives Syria strong influence in the affairs of Lebanon and also promises a redistribution of power cutting sharply into the historic Christian dominance.

The cease-fire agreement establishes a 12-member committee of opposition leaders and Christian leaders who are to begin a dialogue aimed at national reconciliation. Syrian and Saudi emissaries are to attend the conference as observers.

But like the security arrangements, the details of the political meeting had not been worked out today. The Syrian and Saudi roles in the conference, the part Gemayel would play in it, when and where the group would meet, what precisely they would discuss and what they had the authority to decide, remained either vague or in dispute.

Ghassan Tueni, a political adviser to Gemayel, said today that the president would play no active role in the talks.

"The president of the republic, the head of state that is, . . . will not figure as a party to the conversations," Tueni said. "He is inviting various factions and communities to sit around a table."

Former Lebanese president Camille Chamoun, now head of the Christians' umbrella political organization, the Lebanese Front, threatened to boycott the talks because Syria had vetoed participation by Wazzan and speaker of the parliament Kamal Assad in the discussions. Supporters of Assad, a Shiite landowner in southern Lebanon, also began building opposition to the talks.

Leaders of the Lebanese Forces Christian militia, beaten by Druze militias in the early battles in the mountains but still a presence in the eastern sector of the capital, said that while they supported a cease-fire, they did not feel bound by the results of the political negotiations because they were not on the committee.

Robert C. McFarlane, President Reagan's special Middle East envoy, said today he thought the agreement marked the "convening of a true dialogue among leaders of Lebanon." He said he was convinced Gemayel was committed to the cessation in the fighting and that Syrian President Hafez Assad favored an "integrated, unified Lebanon."

Although the confrontations of the past week have pitted the U.S. militarily against Syria, it became clear today that the administration is seeking a rapprochement. The senior official briefing reporters said President Reagan was interested in restoring relations with Syria in the long term. He said Reagan also accepted the premise at the outset of McFarlane's mission here that Syria has legitimate interests in Lebanon.

The Reagan administration has sought to accommodate those interests and seems to expect that that will be the lure in the next stage of McFarlane's mission to get Syria to withdraw from Lebanon.

"The fundamental hope is that a [Lebanese] government can be formed that demonstrates to Syria that its objectives can be met without maintaining a physical presence," the U.S. official said.

Free-lance journalist Marcia Kunstel, in a report made available to The Washington Post, reported from Damascus:

Syrian Foreign Minister Abdul Halim Khaddam said in an interview today that U.S. Marines "must depart immediately" from Lebanon and warned that Americans risk bloodshed and the eventual partition of Lebanon if they maintain a military presence there.

"We believe that for the sake of establishing peace, stability and security in Lebanon and for the sake of international peace and security, as well as for the sake of the security of the American citizens who are in the Marines, they must depart," Khaddam said.

He also said the rest of the 5,400-member multinational peace-keeping force should withdraw.

"This matter was not raised during the cease-fire discussions, although there is a common or joint conclusion between us and the Saudis that the Marines must depart," said Khaddam. His contention regarding Saudi view could not be confirmed here immediately.

Staying in Lebanon will risk even deeper American involvement, leading to "a Vietnamization of Lebanon, which would require an ever larger fighting force," he said.

If the Marines are further embroiled, "the U.S. administration will be compelled to send 10,000 others more, and hence it will sink in the region. And the American citizen will pay a lot of blood for an issue is none of his concern," Khaddam warned. He spoke directly of the Marines, but under questioning said he meant the entire peace-keeping force should leave Beirut. Others in the force come from France, Italy and Britain.

He did not criticize American conduct in the past few days of hostilities in Lebanon, when U.S. Marines and Navy vessels anchored off Beirut shelled antigovernment positions.

Both American and Lebanese military figures in Beirut had said the American shelling was against guns behind Syrian lines in eastern Lebanon, that the rockets were intended to knock out "Syrian guns."

But Khaddam maintained that no Syrian post was targeted by the U.S. forces and no Syrian soldiers were engaged in the Lebanese hostilities. Western sources here estimate Syria has 50,000 to 60,000 soldier in Lebanon.