Secretary of State George P. Shultz announced yesterday that Richard W. Murphy, his assistant secretary for Mideast affairs, will visit the region soon to explore recent proposals for renewed Arab-Israeli talks and to report on the prospects for active U.S. involvement in trying to revive the peace process.

Shultz, speaking at a news conference, also said that, despite the pullout Thursday of most of the remaining personnel at the U.S. Embassy in Lebanon, "we don't intend to be pushed out of a region by terrorist threats."

"We have an important representational job to do in Lebanon, even under the current circumstances, and we intend to do it," Shultz said. "At the same time, there is no point in having more people than you need in a situation where there is danger. So the two considerations combine to lead you to reduce the presence for now . . . . "

The announcement that Murphy will go to the Middle East was in response to an attempt earlier this week by Egyptian President Hosni Mubarak to persuade President Reagan to seize new Arab overtures as a means of revitalizing the moribund peace process.

However, Shultz made clear that the Reagan administration wants to know a lot more about the thinking and flexibility of the Arabs and Israelis before it embarks on a new activist course in the Middle East. Underlying this caution, U.S. officials have said, is remembrance of the failure that overtook Reagan's 1982 initiative for a comprehensive Mideast solution and the 1983 Israel-Lebanon peace agreement worked out with Shultz's mediation.

Mubarak, in his latest White House visit, outlined a plan for a three-stage negotiating process starting with "discussions" by a Jordanian-Palestinian delegation and leading eventually to negotiations with Israel on resolving the future status of Israeli-occupied Arab territories.

"President Mubarak's suggestion is one suggestion; there are a number of others," Shultz said in elaboration of the U.S. position. "I think it is fair to say that there has been movement among the parties in the region . . . . It's important to try to keep this momentum going, and Mubarak deserves credit for helping to get it going."

Shultz noted that Jordanian Prime Minister Taher Masri will be here for talks next week and added that Murphy will travel to the region soon afterward.

"He'll go to Israel, he'll go to Egypt, he'll go to Jordan, he'll go to Saudi Arabia, he will visit other countries, and he will continually assess developments," Shultz said. "He will report back promptly, and we will be doing everything that we can to keep the momentum toward peace in the Middle East going."

A senior U.S. official, who asked not to be identified, later described Murphy's mission as a time-buying measure that will enable the United States to postpone a decision while it seeks to clarify the many ambiguities in the proposal brought by Mubarak and to gauge its prospects for success.

"The word that is coming back to us about the agreement" between Jordan's King Hussein and Palestine Liberation Organization Chairman Yasser Arafat "is that they have gone as far as they can go and that it is now up to an outside force like the United States to push the process further," the official said.

"But, our first question has to be whether there is room for them to go still further," he added. "We need a better fix on the political parameters that they can operate in . . . . We also need to know whether Israel, which is trying to manage two crises right now withdrawal from Lebanon and severe financial problems , can take on a third major issue."

In discussing the Lebanon situation, Shultz reiterated U.S. support for President Amin Gemayel's attempts to cope with a mutiny against his authority from some of the Christian militias that form the support base of his Christian Phalangist Party.

"We continue to advocate a free and independent Lebanon, with all the foreign forces removed, and with arrangements that will look to the security along Israel's northern borders," Shultz said.

"Obviously, the security situation is a tense one for everybody, not just Americans," he said in reference to threats from Moslem extremists and the danger of new civil war. He added that when tensions ease, "we would reintroduce people who would have a role to play in helping Lebanon reconstruct itself and be the prosperous place that it once was."

The senior official said that while the administration is reassessing the position of Ambassador Reginald Bartholomew and the remaining embassy personnel in Beirut on a day-to-day basis, he believes that there currently is no need to end the official American presence there.