Administration spokesmen yesterday publicly tried to damp down speculation that there was cause for alarm in the recent comings and goings in Lebanon.

Intelligence officials privately also took a calm view of recent Syrian and Palestine Liberation Organization movements into the country.

"I don't see that there is any sign of viewing with alarm the situation over there at this time," said Henry E. Catto Jr., assistant secretary of defense for public affairs, at a Pentagon news briefing.

His answer came in response to television reports Monday night that PLO fighters were returning to Lebanon in significant numbers.

"I have nothing to confirm that there is a PLO buildup," said Catto.

As for Syrian troops moving into Lebanon in worrisome numbers, Catto said: "Nobody has any strong feeling that there are additional troops being brought in, that there is a war fever or anything of that sort."

The Pentagon spokesman also contradicted a claim by an Israeli official that the evacuation of Soviet dependents from Beirut was intended to create a war scare to impel Israeli troops to leave Lebanon.

"The Soviets have explained it as routine operations," said Catto. He said he had "no reason" not to believe them.

Catto in another exchange with reporters said administration officials are not alarmed about Soviet threats to intervene directly in Lebanon if Arab forces are attacked.

"The Soviets frequently say things for propaganda purposes," he said.

Nobody views the current situation in the Middle East "as being particularly alarming," he said.

State Department spokesman Alan Romberg said "there has been some movement of Syrian forces and personnel into Lebanon but no sign that Syria is preparing to attack. There has clearly been some reintroduction of PLO forces into Syrian-controlled areas of Lebanon."

Administration sources told The Washington Post that intelligence officials learned of a convoy of 600 to 800 Syrians and PL0 fighters that moved into Lebanon's Bekaa Valley last Thursday. But they said there has been no hard evidence since then that this was more than a rotation of forces.

Officials added that there was no sign that the Soviet Aeroflot airline was adding flights to evacuate Russians from Beirut.

When the Middle East situation becomes particularly intense, presidents often send extra aircraft carriers toward the trouble area. But there was no sign of this yesterday.

Pentagon sources said the U.S. aircraft carrier Nimitz has left the Mediterranean on its way home to Norfolk, the carrier America is also homeward bound from the region and the carrier Eisenhower is steaming eastward in the Mediterranean as planned.