Assistant Secretary of State Richard W. Murphy's latest trip to the Middle East made so little progress that the Reagan administration has started to reassess its hopes of reviving the Mideast peace process.

According to knowledgeable diplomatic sources, Murphy was unable to win assurances that if the United States agrees to meet with a joint Jordanian-Palestinian delegation, direct talks between Jordan and Israel would follow. He is understood to have found Israel and Jordan unwilling to compromise on positions that the United States regards as incompatible with the objective of launching new Arab-Israeli talks by the end of the year.

The sources stressed that the administration is not ready to abandon the goal of expanded peace talks to which the United States has devoted considerable effort since Jordan's King Hussein met President Reagan at the White House last May.

But, the sources said, the administration will not be able to put off much longer a decision about whether to risk serious strains in U.S. relations with Israel by acceding to Hussein's wishes and meeting with the joint Jordanian-Palestinian delegation, a course that, according to Murphy's findings, still does not offer any guarantee of ending in direct talks between Jordan and Israel.

Israel strongly opposes U.S. acquiesence to Hussein's proposal because it fears that such a meeting would be regarded as U.S. recognition of the Palestine Liberation Organization (PLO). In an effort to reassure Israel, the United States has pledged that it will not deal with any delegation containing PLO members and will go ahead with a meeting only if it appears to further the goal of eventual Jordanian- Israeli talks.

However, Murphy is known to have been unsuccessful in obtaining a clear-cut commitment from Hussein to such an end result. Instead, the king is understood to have said that while he hopes his plan will lead to eventual direct talks, the uncertainties of continued cooperation from PLO chairman Yasser Arafat and the reluctance of moderate Arab states to support his peace initiative openly prevent him from giving any assurances about what Jordan eventually will do.

Hussein also is known to have been unyielding on two demands that the United States regards as serious obstacles: Jordan's insistence that the United States deal with the PLO and that the peace talks be held under the umbrella of an international conference including the Soviet Union.

Israel will not take part in any process that includes the PLO, and the United States opposes any Soviet involvement in Mideast negotiations at this stage.

On the eve of Murphy's departure to the Middle East early last week, U.S. officials expressed cautious optimism that he might find sufficient flexibility in the Jordanian and Israeli positions to get around the procedural problems.

That didn't happen, and the question facing U.S. policymakers is whether further give is possible or whether the process finally has reached a point where it is not susceptible to further movement.