Casting the United States and Egypt in the villain's role, Arab foreign ministers met here today to plan retaliation against Egyptian President Anwar Sadat for signing a peace treaty with Israel and against the Americans for helping bring it about.

They will be joined Wednesday by ministers of economy as the Arab states, collectively shocked and bewildered by Sadat's dramatic gesture, search for some coordinated approach to their next move.

Despite waves of protest rolling across the Arab world and the apparently genuine distress of many Arab leaders, however, it remains questionable whether they can take any effective action against Sadat here or in any other forum.

As in previous Arab portest gatherings against Sadat's dealings with Israel, the key appears to lie with Saudi Arabia, which is a major financial backer of Egypt and a military and strategic partner of the United States.

In an indication of pressure building on the Saudis to join collective Arab measures against Egypt, Iraqi Vice President Saddam Hussein told the conference today that there is no longer any room for neutrality about Egypt, and that "anyone who collaborates with Sadat is a collaborator with the Zionist enemy."

In the past, the Saudis have joined other Arabs in criticizing Sadat's peace moves. But they have quietly continued their economic and political ties to the Egyptians.

The retaliatory measures against Egypt being called for in predictable rhetoric here did not deter Sadat from making peace. And many of the individual countries called upon to join coordinated Arab action against the United States have strong bilateral ties to Washington-particularly the Saudis.

It appeared likely that the foreign and economic ministers would adopt resolutions calling for carrying out sanctions against Egypt approved at an Arab summit conference here last November after Sadat signed the Camp David agreements.

These reportedly call for transferring Arab League headquarters out of Cairo-a move Egypt preempted today by announcing suspension of its membership-and a boycott against companies that do business with Egypt.

Hussein said the time has come to prove that these were "not paper resolutions." In Egypt, however, officials have expressed confidence that the other Arab states have very little ability to inflict real economic damage on Egypt unless the Saudis withdraw their military aid. Egyptian trade with the other Arab countries is minimal and over the past two years the Sadat government has greatly reduced its dependence on Arab economic assistance.

In addition, the Arab countries themselves count on Egyptian laborers to build their buildings and operate many of their facilities-a relationaship symbolized today by an Iraqi Airways jumbo jet loading Egyptian workers at Cairo airport for a flight to Baghdad.

Yasser Arafat, leader of the Palestine Liberation Organization, called, as expected, for Arab oil states to impose a petroleum and trade embargo against the United States. Hussein said the peace treaty, which he called a "treaty of surrender," would not be implemented "without consequences for the United States."

In a press conference after the meeting, Iraq's foreign minister, Saadoun Hamadi, said he personally believes Arafat's call was "relevant" and will be discussed.

But any such move would require the collaboration of Saudi Arabia. The Saudis, although unhappy about the peace treaty and rapidly distancing themselves from American Middle East policy, are considered by Egyptian and American officials as unlikely to do anything so drastic as to provoke an oil crisis and jeopardize their American arms supplies.

In addition, the Saudis would be uncomfortable if a radical or revolutionary government were to replace Sadat and the Egyptians believe the Saudis are unlikely to jeopardize their own interests by tring to bring down Sadat.

The conference is taking place in Baghdad's Palace of Peace, sealed off by security forces. Reporters have almost no access to delegates and little basis aside from public statements on which to judge collective sentiments.

The fact that the meeting is being held here, however, further enhances Iraq's attempt to cast itself as the political and ideological center of the Arab world. Reconciled with Syria, in the forefront of opposition to Sadat, a leading oil exporter, and on good terms with Saudis, the Iraqis are emerging as the center of the collective Arab action and sentiment now that Egypt has thrown aside all claim to Arab leadership.

Tens of thousands of Iraqis, including students, soldiers and workers, staged an organized march through Baghdad's streets today to protest the peace treaty. "Sadat is not an Arab," they shouted. "This treachery must be avenged."