BAABDA, LEBANON, OCT. 14 -- Hoping to restore peace following the surrender Saturday of rebel Gen. Michel Aoun, Lebanese officials said today that President Elias Hrawi would press efforts to end the country's 15-year civil war by forming a national unity administration that would include the chiefs of Lebanon's main militias.

Hrawi is committed to implementing a peace plan approved by the legislature last year and aimed at restructuring the power-sharing formula among Moslems and Christians worked out at the founding of the modern Lebanese state in 1943. Hrawi's spokesman, May Kalahi, said today that the warlords would be included in the new cabinet so they can "take part in the decision to disband their own militias."

Aoun's ouster was being hailed here today as bolstering Hrawi by allowing the Syrian-backed president to extend his authority over Christian areas that had been loyal to the staunchly anti-Syrian Aoun. But even before consultations for the new government could begin, signs emerged that the task of taming Lebanon's warring militias would remain difficult.

Walid Jumblatt, leader of the Moslem Druze force, and Samir Geagea, a Christian militia commander who had opposed Aoun, renewed verbal attacks on one another today, and some residents expressed fears that Syria's current domination of Lebanon would lead only to more conflict. The peace plan provides for the disarming of the militias but sets out no timetable for Syrian withdrawal from all of Lebanon.

One analyst cautioned that thus far in Lebanon's long war, all attempts to "demilitarize the militias have been costly farces that usually end with bloodshed only to start up again later."

As the main power broker in Lebanon, Syria, whose air and ground attack on Aoun's headquarters Saturday precipitated the general's surrender, extended its control today over Christian east Beirut. Hrawi had asked Syria, which has maintained troops in Lebanon since 1976 and controls much of the country, for help in driving Aoun out of the presidential palace.

Lebanese analysts said Syria, which had long sought to end Aoun's rebellion, finally decided to attack this weekend in part because it felt emboldened by its alliance with the United States in the multinational force facing Iraq in the Persian Gulf. In the past, analysts said, Syria had refrained from moving militarily against Aoun because it feared Israeli retaliation and U.S. disapproval.

Syrian soldiers wearing netted helmets and carrying confiscated U.S.-made M-16 rifles set up checkpoints and directed traffic. The Syrians also took control of the presidential palace Aoun had occupied, stopping people today at the gate as high-ranking Syrian officers sat under the shade of pines surveying the steep winding road leading to the battered structure.

The once-scenic road leading up to the palace, located on the outskirts of Beirut, is now lined with tanks and littered with ripped branches and leaves. Craters could be seen beneath charred pine trees still smoking from Saturday's Syrian bombardment.

While it is believed that Hrawi would like to move his headquarters from Moslem west Beirut into the presidential palace, Syrian troops said today they expected to use the structure for the time being.

"We are going to live for a long time under oppression and the Syrian boot," complained Houda Bejjani, a university student. Asked whether Syrian dominance could bring peace to Lebanon, she shook her head as she poured water in cans to carry up to her apartment.

Aoun, who had considered himself the legitimate leader of Lebanon and had refused to accept the peace plan because it failed to guarantee Syrian withdrawal, remained today in the French Embassy in Beirut, where he was granted asylum. Members of Aoun's three-man military cabinet were hiding with him and his family at the embassy.

Lebanon and France, the traditional ally of Lebanon's Christian Maronite community, quarreled over his fate. Lebanese officials insisted that he must be tried on charges of embezzling millions of dollars in state funds and harming the public interest, while French authorities sought permission to evacuate the general to France.

Sources close to Hrawi said French Foreign Minister Roland Dumas telephoned the Lebanese president twice Saturday and French Ambassador Rene Ala visited him today. Lebanese officials said Hrawi's government is afraid that France will provide Aoun with a political platform to attack the regime and portray himself as a champion of Lebanon's Christian community.

Government officials close to Hrawi said a file was being compiled to present to judicial authorities on Aoun's alleged misappropriation of public funds. Aoun is said to have a sizable bank account in a French bank as well as accounts in the names of his ministers.

Aoun had imposed his own taxes in recent months in the part of the Christian enclave he controlled, and used contributions from supporters to pay soldiers after the central government refused to extend him funds. He collected levies and real estate tariffs in cash and refused to deposit them at Lebanon's central bank.

The peace plan was agreed to among Lebanese Christian and Moslem legislators meeting last year in Taif, Saudi Arabia. It gives Moslems, now a majority of the country's population, equal power with Christians in a future Lebanese government.

The old formula gave the balance of power to the Christians, and demands for change by the Moslems were a chief reason for the outbreak of civil war in 1975. Since then, Moslem and Christian militias fought each other, and rival organizations within each community also have battled each other.

In addition to forming a new cabinet, Hrawi is expected to expand the present parliament of 99 seats to 108 by appointing replacements for thelegislators who have died since the last election, held in 1972, and by adding Moslem legislators to strike an even balance with the Christians.