Israeli war planes today staged their second air raid in five days against suspected Palestinian targets in southern Lebanon despite American entreaties to exercise maximum restraint during the current Middle East missile crisis.

Local residents said at least six persons were killed and nine wounded in the 45-minute midday attack at Abul Aswed just north of the Litani River along the Mediterranean coast.

Israeli military spokesmen said the target was a regional headquarters of Fatah, the mainstream guerrilla outfit headed by overall commando leader Yasser Arafat.

Six U.S.-built Phantom F4 fighter-bombers rocketed a three-story building and released thermal balloons to deflect heat-seeking missiles fired from the ground, the residents said.

The Israeli Army command in Jerusalem said the Israeli pilots reported "accurate hits" on the building, which was occupied at the time. All of the aircraft returned to base, he added.

After a month's interruption because of the missile crisis, Israel last Thursday resumed its controversial preemptive strike policy less than 24 hours after U.S. presidential trouble-shooter Philip C. Habib had left Tel Aviv for Washington. That attack killed some Libyans at a missile site near Beirut.

When the U.S. administration did no more than insist on maximum restraint, Israeli Prime Minister Menachem Begin said he had told Habib he would not stop bombing Palestinian targets.

Lt. Gen. Rafael Eitan, the Israeli chief of staff, followed suit and today Fatah, often spared in past Israeli attacks in favor of more radical Palestinian groups, was hit.

A Lebanese minister, who declined to be quoted, voiced fears that Israel was seeking to exacerbate the increasingly volatile situation in Lebanon.

He suggested Israel was seeking to cause maximum embarrassment for Egyptian President Anwar Sadat before his meeting this Thursday with Begin by hitting mainstream Palestinian targets.

"The Israelis don't dare hit the Syrians because they promised Habib they wouldn't before he left for Washington last week, and the Syrians don't dare hit the Israelis for hitting the Palestinians because they don't want to get involved in a larger conflict just because of the guerrillas," he said.

"So everyone hits he who is hittable. Sunday that was why the Christians were shelled -- because the Syrians didn't dare hit the Israelis, and that is why this seemingly low level violence could escalate suddenly."

The minister was referring to exchanges Sunday in which beaches in the Christian sector were shelled, followed by reprisal shellings against those in predominantly Moslem West Beirut. In two days, 30 persons were killed and about 300 were wounded in the ensuing violence.

Although both the leftist National Movement, which is allied with Syria, and the Israeli-supported rightist Christian Lebanese militia agreed last nigbht to stop shelling residential areas, past experience is replete with examples of violence against such targets.

Renewed violence could jeopardize a four-power meeting Saturday designed to find solutions to the Lebanese crisis. Participating in the meeting to be held south of Beirut would be Saudi Arabia and Kuwait as well as Lebanon and Syria, which maintains 22,000 troops here as peacekeeping forces with Arab League backing.

Success of that meeting is considered part and parcel of the mission Habib will resume when he returns to the Middle East later this week.