The United States yesterday condemned the terrorism against El Al Airlines at the Rome and Vienna airports as "vicious attacks that deliberately and indiscriminately killed innocent people." While U.S. officials publicly refused to assign blame, they said privately that the initial evidence points to a Palestinian terrorist group known as Abu Nidal.

The officials, while emphasizing that more information was needed before deciding on next steps, nevertheless declined to say that the United States would oppose some form of retaliation if the identities and whereabouts of those responsible could be established.

In the meantime, the United States was understood to be cautioning Israel to wait until the situation is clearer and not to attempt generalized retaliatory moves that might hit the wrong people or place new obstacles in the path of efforts to restart the Middle East peace process.

The officials, who declined to be identified, said the preliminary suspicion that Abu Nidal was responsible for the attacks is based largely on deductive factors because the group, a breakaway faction of the Palestine Liberation Organization, follows a practice of neither claiming nor denying responsibility for its terrorist activities.

The officials noted that the indiscriminate nature of the attacks fits the pattern of past Abu Nidal operations. In addition, the officials said, U.S. intelligence services believe that in recent months Abu Nidal has been working closely with Libya to mount a new Mideast terrorism campaign.

Some members of the U.S. intelligence community believe that the hijacking of an Egyptian airliner to Malta last month was carried out by Abu Nidal members with Libyan support, the officials said. That incident resulted in the death of 60 people after Egyptian commandos stormed the plane.

Yesterday, the administration asserted that the Rome and Vienna attacks underscore the need for concerted international action against terrorism. State Department spokesman Charles E. Redman issued a statement that said in part:

"This latest outrage demonstrates again that terrorism threatens all nations. In line with the resolution passed unanimously earlier this month by the United Nations General Assembly, we call upon all members of the world community to join us in combatting forcefully these criminal acts and bringing to justice those responsible. There must be no place for terrorists to hide.

"Terrorists who kill and maim innocent civilians are beyond the pale of civilization and must be held responsible for their crimes, which no cause can justify. People and nations who respect decency and humanity have a common obligation to work together to end this menace."

At the White House, presidential spokesman Larry Speakes said, "We would hope that those who are responsible for this cowardly act would be apprehended and punished to the fullest extent."

Redman acknowledged that the United States recently circulated to airports around the world a "generalized" warning of possible terrorist threats against unspecified targets. He declined to elaborate, but other U.S. officials said the message warned that U.S. intelligence agencies had indications of possible "spectacular incidents" being attempted during the Christmas season against Israel, the United States or friendly countries in the Mediterranean area.

Another U.S. advisory distributed last month is understood to have warned that large numbers of terrorists inside Iran were being trained in airplane hijacking techniques. However, U.S. officials said that yesterday's attacks did not appear to be connected to Iran.

The officials added that the Rome and Vienna incidents were especially worrisome because they appeared to signal what one called "an escalation" of past attacks aimed at specific targets rather than random killings. As a result, most airport security measures have been directed toward safeguarding planes on the ground and preventing would-be hijackers from getting aboard flights.

The officials said that the public nature of airport terminal waiting areas and the danger of innocent bystanders being hurt in shootouts have caused most governments to conclude that it is not feasible to station armed guards at ticket counters. They added, though, that Israel does maintain limited armed security at El Al counters in some airports.

Robert J. Aaronson, director of aviation for the Port Authority of New York and New Jersey, which operates John F. Kennedy International Airport, said "the Israelis do have a security presence in their operations at Kennedy," but he declined to describe its extent. Other sources said that armed Israeli guards are permitted within a limited area near the plane under an arrangement with the State Department, which considers the circumscribed area Israeli territory until the plane takes off.

State Department officials, while acknowledging that they were in close contact with Israel, were reluctant to discuss the nature of these talks. However, some officials, noting Israeli government statements blaming the attacks on the PLO, admitted concern that Israel might react in a manner similar to its Oct. 2 bombing of the PLO headquarters outside Tunis.

Abu Nidal, also known as Black June, is led by Sabri Banna, a PLO renegade who took the name Abu Nidal ("Father of the Struggle"). He was expelled from the PLO in 1974 and sentenced to death for allegedly trying to kill PLO Chairman Yasser Arafat.

However, although his organization is openly at war with the PLO, the Israelis have refused to make distinctions between the two groups. In fact, it was the 1982 wounding of Israeli Ambassador Shlomo Argov in London by Abu Nidal attackers that provided Israel with its justification for invading Lebanon on grounds that it was reacting to PLO terrorism.

U.S. officials said the Abu Nidal group, which originally operated from Iraq, moved its headquarters to Syria after 1982. But, the officials added, while it still retains a presence in the Syrian capital of Damascus, it is believed to have been operating since early this year under predominantly Libyan influence and has concentrated its terrorist activities against Jordan and moderate Palestinians, including the mainline PLO elements still loyal to Arafat.