Seaborne Israeli commandos landed on Lebanon's coast at dawn yesterday to destroy a Palestinian guerrilla headquarters, a military spokesman said.

The raid came in the midst of diplomatic activity on the Middle East peace initiatives as well as contacts among the Arabs.

Israel denied that the attack on southern Lebanon was in retaliation for a Palestinian terrorist raid at Maalot Saturday in which an Israeli woman and all three guerrilla infiltrators were killed.

The raid 12 miles north of the border apparently resulted in no casualties. A Palestinian spokesman said the building blown up was a farm house, not a guerrilla base.

In jerusalem, passersby spotted an explosivespacked car parked on a busy shopping street. Demolition experts defused the time bombs.

On the diplomatic front, King Hussein of Jordan held talks in Damascus with Syrian President Hafez Assad, reportedly on the developing alliance between Syria and its formerly estranged neighbor, Iraq.

U.S. envoy Alfred Atherton arrived in Tel Aviv in a renewed effort to revive the stalled Middle East talks between Israel and Egypt. A major issue is Israeli occupation of the West Bank of the Jordan River.Cabinet Secretary Arieh Naor underlined Israel's position by announcing tht work is to begin in a few days on three new paramilitary settlements there.

A Carter administration official said in Washington that the United States sent a "strong protest" to Israel over the settlements. The decision to build them as Atherton launches his effort "doesn't make his job any easier," the official said.