Israeli jets today destroyed another Syrian SA9 surface-to-air missile battery in eastern Lebanon in what appeared to be retaliation for the killing Sunday of six Israeli soldiers in an ambush near Syrian lines east of Beirut.

Also today, President Amin Gemayel named Shafiq Wazzan, the outgoing prime minister, to head the new government. As he held negotiations last week on the choice of prime minister, Gemayel had been reported to be favoring the commander of the internal security forces to replace Wazzan, but he apparently changed his mind and renamed Wazzan to the job to please Moslem leaders in West Beirut.

The Israeli jet raid was the first attack on Syrian positions in Lebanon since Sept. 13. The Israeli military command said the planes wiped out a mobile launcher on top of Dahar el Baidar mountain, which overlooks the Bekaa Valley along the main Beirut-to-Damascus highway.

It came only a few hours after an emergency Israeli Cabinet meeting called to discuss the ambush of a bus bringing vacationing Israeli soldiers back to duty. The Cabinet reportedly decided to react cautiously to the attack. Details on Page A15.

Besides the six deaths, 22 Israelis were injured in the ambush, one of the highest tolls inflicted upon the Israelis since they launched their invasion of Lebanon June 6.

The gunmen, shooting from behind a wall, still have not been found, an Israeli Army spokesman said here today. But, he added, "we think they are PLO Palestine Liberation Organization people." He suggested they might have come from West Beirut rather than from behind Syrian lines to carry out the ambush near Alayh, six miles southeast of Beirut.

The Phalangist radio station and Lebanese Army sources reported Israeli jets had also attacked Syrian and Palestinian guerrilla positions at two other places in the mountains east of Beirut. But the Israeli military statement made no mention of any other targets hit.

State Department spokesman Alan Romberg said in Washington that the United States "deplored" the Israeli attack and indicated that the White House looked upon it as a retaliation to the bus ambush, The Associated Press reported. "It underlines the importance for all parties to work together to seek rapid withdrawal of all foreign forces from Lebanon," Romberg said.

In Damascus, a Syrian military spokesman said the air attacks violated the Lebanese cease-fire agreement, United Press International reported. "But the air defense has prevented the enemy from carrying out its goals," the spokesman added.

Despite the violence in eastern Lebanon, officials in Beirut were working to establish a government to serve under Amin Gemayel.

Wazzan, 57, a Sunni Moslem lawyer, was the unanimous choice of West Beirut Moslem leaders to again take the job of prime minister. Gemayel reportedly favored Gen. Ahmed Hajj, from the internal security force, for the job but changed his mind after a secret meeting with former prime minister Saeb Salam during the weekend. At that meeting Gemayel was told of the Moslem opposition to Hajj because of his assumed sole concern with law and order.

Under a national agreement dating from 1943 dividing power among Lebanon's religious factions, the country's president is to be a Maronite Christian and the prime minister a Sunni Moslem while the speaker of the parliament should be a Shiite Moslem.

Wazzan played a central role in the negotiations through the summer that led to the evacuation of Palestinian guerrillas from West Beirut. He and Salam served as the main intermediaries between the PLO and the United States.

A timid, self-effacing person when he first became prime minister under former president Elias Sarkis in October 1980, Wazzan came to assert himself forcefully first about the need for the Syrian peace-keeping forces to get out of Lebanon and then during the summer against the devastating Israeli bombings of West Beirut. He is credited by the Lebanese Moslems with having saved West Beirut from an even worse fate.

Speaking to reporters as he emerged from the presidential palace after his nomination, Wazzan said he wanted to "leave slogans aside." He added that "what we need now is to work."

Later, at a brief press conference at his home, Wazzan said the new government was committed to establishing Lebanese sovereignty over all Lebanese territory and that this meant the remaining militias, both Christian and Moslem, "must disappear in one way or another."

He was referring to Christian Lebanese Forces militia still operating in East Beirut and a number of Moslem and Christian units still in the northern city of Tripoli. At least 14 people have been killed and more than 20 injured in fighting between pro- and anti-Syrian factions during the past two days. Wazzan also said the new government would insist on the withdrawal of "all non-Lebanese troops" from Lebanon.

Regarding the fate of 500,000 Palestinian civilians in Lebanon, Wazzan said he favored a "special status" for them since they were "Arab brothers." But he hinted this should be no different than that given to all other foreign Arab nationals.

He said the new government planned to take up the issue of the Palestinians' status in the country directly with the PLO and promised to allow the U.N. Relief and Works Agency to continue looking after their needs.

Wazzan sought to play down the wave of arrests among Palestinians in the West Beirut camps where massacres took place last month, saying it was part of a campaign to weed out all foreigners who did not have proper identity cards or residence permits. Reports here say between 600 and 1,500 foreigners, the majority Palestinians, have been detained by the Lebanese Army during the past two weeks.