Speaking shortly after Israeli warplanes flew over Beirut for the second time today, Palestinian leader Yasser Arafat defiantly challenged the Israeli leadership to come ahead with a widely predicted attack on Palestinian forces in Lebanon.

"I say while the planes circle, welcome, why have you delayed your attack," Arafat told a Palestinian guerrilla rally. "In this difficult time in Arab history I say that our decision in the joint forces is that not a single rifle will remain in storage and no bombs underground. We will fight until the last bullet and the last cannon and the last fighter."

The bravura came against a background of Arafat's own predictions that Israeli forces plan a heavy attack on guerrilla positions in southern Lebanon and Beirut within a few days. As if to underline the fears, Israeli warplanes streaked high over Beirut shortly after dawn this morning, drawing futile Palestinian antiaircraft fire, and passed again this afternoon just 10 minutes before Arafat addressed the rally marking the 17th anniversary of the Popular Front for the Liberation of Palestine-General Command.

The General Command, headed by a former Syrian Army officer, Ahmed Jebril, is on the left wing of Arafat's overall Palestine Liberation Organization. Its leadership is reported among the PLO officials who are urging Arafat to abandon a U.S.-sponsored cease-fire on the Israeli-Lebanese border that has helped maintain calm since July last year.

In a reminder of these strains, military authorities announced in Tel Aviv that an Israeli patrol captured two Palestinian guerrillas trying to enter the occupied West Bank from Jordan Friday night. The Israeli government has said it considers such attempted attacks to be cease-fire violations and has warned it will strike at PLO targets in Lebanon if they continue.

The U.S. ambassador to Israel, Samuel Lewis, quoted Israeli Prime Minister Menachem Begin as saying Sunday that the Israeli government had taken no decision to strike at Palestinian guerrillas in Lebanon, Reuter reported. Lewis' remarks followed a three-hour meeting with the Israeli leader.

"He assured me that the Israeli Cabinet has taken no decision to go into Lebanon in any way, shape or form," Lewis said in a statement.

Israel's Cabinet met for seven hours Sunday, and state radio reported that southern Lebanon and relations with Egypt were believed to have topped the agenda.

Arafat's strong words seemed to be part of his standard recipe for morale-building. At the same time, his repeated references to an Israeli attack fit into what PLO officials portray as genuine concern that the Jewish state is about to launch a tough blow against the 15,000 full-time Palestinian guerrillas under Arafat's command and their leftist Lebanese allies grouped in the "joint forces."

"The Israeli command speaks of new and advanced fighting tactics, and I tell them they will fail because we also have advanced our fighting tactics and so we are both in the same field," Arafat told the General Command rally.

"Despite claims that they have the strongest army in the area, I tell them it is still part and parcel of the American Army and itself needs to use highly developed tactics to face the joint forces. Just as we taught them a lesson during the eight-day and 15-day wars, we will teach them more lessons in the coming war."

The eight-day and 15-day wars refer to Israel's March 1978 invasion of southern Lebanon and the two weeks of artillery exchanges that followed Israel's bombing in July of PLO offices in Beirut that killed nearly 300 persons. Because they were not crushed in those encounters, many Palestinian officials point to them as victories.