Palestinian leader Yasser Arafat agreed today to accept a cease-fire in the current upsurge of fighting with Israel but only on the condition that Tel Aviv abandon its policy of preemptive strikes on guerrilla strongholds inside Lebanon and also stop overflights of Palestinian positions.

Arafat's position, published in a local newspaper and confirmed by an official of the Palestine Liberation Organization, came as the guerrillas and Israeli Army continued exchanges of heavy artillery and rocket fire across the Lebanese border.

A Palestinian military spokesman announced late tonight that an Israeli sergeant had been captured in the fighting of an attempted commando landing near the Zahrani River early yesterday morning. If true, it is believed to be the first time that Palestinian guerrillas have captured an Israeli commando in ground combat, although an Israeli soldier was captured after the 1978 Israeli invasion of southern Lebanon.

Palestinian sources hinted that the captured sergeant might be put on display before journalists and that other Israelis might have been taken prisoner by the guerrillas in the past few days. They refused to elaborate.

Despite 12 days of Israeli air, artillery and naval attacks on Palestinian strongholds in the south and around Beirut, the guerrillas have still not ceased their shelling of villages in northern Israel with long-range artillery and Katyusha rockets. Five Israeli civilians have been killed and another 50 wounded.

Meanwhile, press reports here today said Syria was coming under considerable pressure from visiting Palestinian as well as leftist Lebanese delegations to bring SA6 missiles to the defense of the Lebanese capital. It was Syria's stationing of similar ground-to-air missiles in Lebanon's eastern valley that touched off the crisis between it and Israel in late April.

Israel has insisted they must be removed because they threaten the free movement of its aircraft over southern Lebanon, but Syria has refused saying the missiles are purely defensive and for the protection of Syrian peace-keeping troops stationed in Lebanon. Lebanese press accounts and statements from Christian militia leaders indicate that there is strong resistance in Lebanon to shifting the missiles into Beirut.

Arafat relayed his conditions for an end to the fighting to the commander of the United Nations peace-keeping force, Maj. Gen. William Callaghan, during an hour-long meeting last night devoted to discussion of a possible cease-fire, according to the Beirut daily newspaper Al Liwa, which is usually well-informed on Palestinian affairs. A PLO spokesman confirmed the account.

Arafat's terms, which are unlikely to be easily accepted by Israel, give an indication of the difficulty U.S. special envoy Philip C. Habib faces in arranging a halt in the fighting, the worst between the Palestinian guerrillas and Israel in three years.

Habib was expected to arrive here early Wednesday after a third round of talks in Tel Aviv tonight with Israeli Prime Minister Menachem Begin about a cease-fire. Habib's mission has been all the more complicated by the fact the United States refuses officially to recognize the PLO or have any diplomatic dealings with it.

Instead, he will have to use intermediaries such as the Lebanese government, Saudi Arabia and possibly Syria in his negotiations with the Palestinian organization. The indications today were that the Saudis were already actively engaged in the search for a cease-fire, using their diplomatic leverage both with the United States and PLO's backers.

The Saudi ambassador to Lebanon, Ali Chaer, was quoted today as saying Saudi Arabia is using "all the influence and audience" it has with Washington to get the U.S. government to pressure Israel into ending raids on Palestinians in Lebanon.