An atmosphere of frustration and self-doubt overshadowed the usual professions of determination and solidarity as Arab foreign ministers gathered here today for a special meeting.

Delegates from 21 countries and the Palestine Liberation organization assembled in the ballroom of the Hilton hotel. This meeting had been scheduled for September in anticipation of a Geneva Middle East peace conference but the continuing uncertainty about the timing of that event has made it unclear what the foreign ministers expect to accomplish here.

Members of several delegations acknowledged that the real issues confronting the Arab world at this time - the Geneva conference, the Israeli air raids into Lebanon and the explosive conflict between Morocco and Algeria - are beyond the reach of this gathering.

The vaguely worded agenda says the delegates will consider ways to promote Arab unity and solidarity and will also promote Arab unity and solidarity and will also set the agenda for an Arab summit conference. But Egypt is opposed to holding a summit conference now, and is expected to hold out against preparing an agenda for one until the prospects for a Geneva conference are clearer.

An apparent attempt by Egypt to delay a summit was outflanked by the selection of a seven-member committee to clear away procedural issues and report back on Sunday.

Tunisian Prime Minister Hedi Noueira seemed to set the tone this conference in his opening address, "The Arab world is in a very difficult situation," he said. "I am not exaggerating to say it is the most difficult we have ever known," He said the conflicts within the Arab world have "raised within doubts about our own selves and our abilities.

Noueira expressed the conviction that the Arabs could overcome these conflicts and prevail over Israel as well if they performed up to their potential, but prospects for any decisive actions at this conference appear slim.

Prince Saud Fiesal the foreign minister of Saudi Arabia, condemned this week's Israeli air raids into Lebanon as "barbaric". Mahmoud Riad, the secretary general of the Arab League accused Israel of "criminal aggression" aimed at sabotaging efforts to implement a cease-fire in south Lebanon. Authoritive officials said they expect the conference to pass a resolution condemning the Israelis in strong terms, but no one has any illusions about the effect such a move will have.

The feud between Algeria and Morocco and the threat by Morocco's King Hassan to send troops into Algeria in pursuit of Polisario guerrillas has proved to be an embarrasment to the host Tunisians and to the conference organizers.

Tunisians officials say the host governemnt has asked that the feud be kept off the official agenda because there is nothing the delegates could do that would be effective and any action might anger one or another of the quarreling Arab neighbors.

King Hassan has sent Secretaery General Raid a letter to be circulated here that reportedly accuses Algeriq of aggression against his country but it is considered unlikely that the con- ference will deal with this directly, delegates said.

Arab officials said they believed both countries would be grateful for a face-saving way out of the feud, but the best hope for achieving this was private medaition of the kind currently being undertaken by Vice President Hosni Mobarak of Egypt.

Secretary General Riad is expected to propose team the creation of a standing diplomatic team that the Arab League would send to deal with such regional disputes in the future.

As for Geneva, it seems clear that, as one delegate put it, "That game is being played on another arena," a reference to Egyptian President AAnwar Sadat's forthcoming visit to Syria in which those two key countries are to set their joint negiotiating posture.

When the foreign miniter's conference was sheduled it was believed by informed anlysts that this would be the forum at which hard liners the Egyptian and Saudi Arabian strategy of negotiating peace with Israel through American mediation.

But now officials here are saying that no such confrontation is likely since the outcome of the Sadat trip to Syria cannot be foreseen and because all the Arabs have come to realize that President Carter, how-anxious for a Middle East peace aggrement does not have free hand in attempting to achieve it.

Sadat appeared to suggest in a speech this week that the Arabs, or at least Egypt were prepared to go to Geneva without the PLO. But PLO delegates to this conference say there is strong sentiment in favor of a resolution reaffirming that the PLO must be invited to participate on an equal basis with other countries.