Jordan today strongly rejected Syrian terms for ending the confrontation along their border, where about 30,000 Syrian troops have been massed since last Thursday in a sabre-rattling exercise matched by a buildup of Jordan's troops.

The Saudi Arabian second deputy prime minister, Prince Abdullah, left Amman for Damascus today after conferring at length with King Hussein and his top advisers in a mediation effort that has not yet shown any concrete results but has helped contain the conflict at the level of angry accusations and military maneuvers.

In Washington, Secretary of State Edmund S. Muskie said the Soviet Union has urged Syria "to cool it," contributing to a lessening of the likelihood of an actual military clash. Muskie said the United States had requested the Soviet Union to use its influence in this situation.

[State Department sources said the U.S. request was made in a meeting Monday between Undersecretary of State David D. Newsom and Soviet Ambassador to the United States Anatoliy Dobrynin. On the same day, the first vice president of the Soviet Presidium, Vasily V. Kuznetsov, arrived in Damascus on a previously arranged trip to exchange certificates of ratification of the recent Soviet-Syrian Treaty of Friendship and Cooperation.]

Abdullah spokes with President Hafez Assad of Syria in Damascus three days ago before coming here.

The Jordanian information minister, Adnan Abu Odeh, angrily rejected press reports that Jordan had agreed to Syria's two main demands. These are that Jordan stop its alleged support for the Moslem Brotherhood, the religious fundamentalist organization Damscus accuses of being behind an 18-month-old attempt to topple the Assad government, and that it drop its alleged attempts to take over representation of the Palestinian people from the Palestine Liberation Organization.

Yesterday, a spokesman for the Jordanian Royal Palace was quoted by Reuter news agency as saying the king had not replied to the Syrian demands but was "open to all reasonable suggestions for resolving this pointless dispute."

Abu Odeh said in a statement today, however, that Syria had not officially presented the reported conditions to Jordan and indicated it could not accept any terms unilaterally imposed by the Syrian government.

Jordan has consistently denied Syrian accusatins that it supports the Moslem Brotherhood and has reaffirmed its support for the PLO as the sole legitimate representative of the Palestinians. Both these positions were reaffirmed by Prime Minister Mudar Badran in an unusually candid and detailed statement to the National Consultative Council here this week.

His statement confirmed reports that Syrian officials has come to Jordan earlier this year, upon the invitation of the Jordanian government, and failed to uncover the Moslem Brotherhood training camps that Damascus claims exist in Jordan with the support of the Amman government.

Officials in Damascus earlier this week repeatedly accused Jordan of backing the Moslem Brotherhood's attempts to bring down the Assad government, charging that this was part of a larger "conspiracy" to liquidate the Palestinian issue and allow Jordan to join in a new Camp David-style negotiating process.

Although the prospects of a Syrian invasion or full-scale war are held to be low by most observers here, a lengthy, if low-key, border confrontation is thought to be likely.

Officials in Syria have said privately that Damascus quietly passed on its accusations of Jordanian support of the Moslem Brotherhood to Hussein at least six months ago, only to have them met with flat denials.

Subsequently, Assad's patience ran out, these officials say, when Damascus perceived an alleged Jordanian shift in favor of a new negotiating process to follow in the footsteps of the stalled Camp David talks in which Jordan would speak for the Palestinians.

Jordan vehemently denies these charges and says that Syrian troop movements since late last week are the result of internal problems that the Assad government is trying to deflect by pointing an accusing finger at foreign-based conspiracies.