Arab reaction to yesterday's joint U.S.-Soviet declaration on the Middle East was cautiously favorably today except for an official silence from Syria, a key element in any peace agreement and a stern holdout in previous U.S. efforts to win Arab support for a resumption of the Geneva peace talks.

The government of President Hafez Assad has strongly resisted the temptation to resume the Geneva conference for its own sake, warning that the risk of failure was great. The procedural compromises outlined in yesterday's joint declaration contain little that is likely to ease those concerns.

Authoritative sources in Damascus said an official comment on the declaration would not be issued until it had been studied carefully.

All of Syria's state-controlled newspapers printed the text of the declaration today, with little comment. They said it contained "postive" points but they also pointed out that in its reference to "such key issues as withdrawal of Israeli armed forces from territories occupied in the 1967 conflict," it did not specify "all" territories.

In that sense, the declaration does not go beyond existing U.N. resolutions, which have been on the books for a decade without bringing about a solution.

Other portions of the declaration did not even come close to meeting Syria's frequently stated minimum terms for going to Geneva. The joint declaration's call for "establishment of normal peaceful relations" among the states of the region, for example, goes well beyond anything Assad has been willing to offer the Israelis.

Syria has been less eager than Egypt to go to peace talks, has taken a consistently harder line in the diplomatic skirmishing and is in a position to influence the response of the Palestine Liberation Organization, which is politically and militarily dependent on Syria.

Reaction from Egypt, Jordan and even the PLO was generally laudatory, with spokesmen and commentators welcoming the American endorsement of the "legitimate rights of the Palestinian people." But the joint declaration was seen less as a break-through than as an important step on a long and difficult road to a settlement.

The conventional wisdom in the Middle East is that Egypt is so anxious to go to Geneva that it would do so under conditions unacceptable to the Syrians. The political and economic troubles besetting the government of President Anwar Sadat are widely believed to make it necessary for him to achieve some notable foreign policy success to shore up his government. But the Egyptians have consistently warned that they will not abandon their support for the PLO and its right to be at Geneva.

The joint U.S.-Soviet declaration does not specify that the PLO should be included in the Geneva conference. It probably could not have, since Israel is pledged never to negotiate with the PLO under any circumstances and President Carter has said that the United States will not talk to the PLO unless it accepts U.N. Security Council resolutations that imply Israel's right to exist. This the PLO has refused to do.

There has been no other official response from Egypt, but this morning the authoritative newspaper Al Ahram criticized the Soviet Union for retreating from its previous position that the PLO must be a full participant at Geneva.

Newspapers in Amman, Jordan, hailed the joint declaration as an important step on the road to peace, but Jordan is in an extremely delicate position in the entire negotiating process.On the one hand King Hussein still nurtures hopes of restoring his sovereignty over the West Bank, even though he has officially accepted the decision of his fellow Arabs to strip him of his claim to it. For that reason he is unenthusiastic about the proposed independent Palestinian state on the West Bank, which the Syrians and Egyptians profess to support.

The king is also aware that many current Israeli officials believe that the proper place for the creation of a Palestinian state is not the West Bank but the East Bank, supplanting the Jordanian monarchy. The king would undoubtedly like to know what is meant by "the legitimate rights of the Palestinian people" before giving the concept his full support.

The joint declaration was deliberately vague on this vital point.

The PLO welcomed it nonetheless as an important concession by the Americans, who have never before endorsed the concept of Palestinian "rights."

WAFA, the Palestinian news agency, said it was a "clear recognition" of the rights of the Palestinian people that would lead to recognition of the PLO. Farouk Kaddoumi, the head of the PLO's political department, welcomed it at the United Nations as a "contribution to international efforts" to obtain a new Security Council resolution supporting Palestinian rights.

Some prominent PLO leaders have criticized PLO Chairman Yasser Arafat for what they saw as a misguided and futile effort to win American support and recogntion, and have been arguing that the PLO's proper course was to align itself more closely with Moscow. That was before the Soviets signed off on a joint declaration with the United States that said nothing about PLO representation at Geneva or the creation of an independent Palestinian state.