President Carter has approved a program of diplomatic and economic measures over the next two weeks in a concerted effort to resolve the long-running Iran crisis without resorting to military action, official sources said last night.

The plan for additional initiatives is reported to have been approved at a National Security Council meeting, with the president in attendance, at the White House yesterday afternoon. No announcements were made at the time.

Some of the additional U.S. steps are likely to be disclosed bit by bit in the coming days. Some other diplomatic initiatives are likely to employ confidential channels that have been maintained throughout the crisis, and may remain secret unless they are disclosed by Iranian authorities.

Several events of the past few days, including the emotional high point of Islamic religious fervor and the voting for a new constitution in Iran and U.N. Security Council session in the international arena, have inhibited the administration from any new steps or announcements.

Now that all these unusually touchy events are behind them, according to the sources, the administration is ready to resume a measured program of steps intended to show activism both to Iran and the American public.

Details of the program were not disclosed.

One facet of the U.S. activism made explicit for the first time yesterday is an intensive, complicated and thus far unsuccessful effort to find a new haven for the deposed shah of Iran, Mohammad Rez Pahlavi.

The acknowledgment of this diplomatic effort, described by an official as "a full-court press" to find a home for the shah for an indefinite period -- followed the disclosure late Monday by House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) that four countries have expressed willingness to receive the shah. O'Neill said he had obtained the information from Secretary of State Cyrus R. Vance.

State Department sources cautioned, however, that security considerations as well as political problems have complicated the search for a new haven for the shah. As of yesterday afternoon, no place acceptable on all counts had been found, the sources said.

Despite the formal offer tendered by President Anwar Sadat, the deposed shah is unlikely to take refuge in Egypt, according to the sources.

The Carter administration is believed to have made clear to Pahlavi that he will be permitted to return to this country when and if the domestic situation in Iran is stabilized, and when his presence here would no longer be deeply unsettling. The administation has also made clear that it will not force him to leave this country if no acceptable haven can be found elsewhere.

In San Antonio, Tex., city oficials last night denied permits for Iranian students to demonstrate against the shah's presence in VIP accommodations at Lackland Air Force Base.

City Manager Tom Huebner said the decision was made after discussions with local, state, military and National Security Council officials in Washington on the grounds that the planned parade might spark violence that could bring harm to the hostages in Iran.

The Ku Klux Klan had sought permits to stage counter demonstrations if the Iranians were allowed to march.

As the captivity of the U.S. hostages passed the one-month mark yesterday, there were these additional developments here:

President Carter warned, in a television message announcing his candidacy for reelection, that "this crisis may not be resolved easily or quickly." He voluntered that "it is possible that in the days ahead our patience and our sense of unity may waver as frustration builds up among us," but pledged he would persevere in efforts to obtain release of the hostages as his top priority.

Carter's message, taped at the White House Sunday, was televised by CBS last night as a paid political announcement.

A White House official told reporters that Iranian militants have threatened some of te hostages with execution if they fail to cooperate. The official would not say when the threat was made or what type of cooperation was demanded.

The statement, like several others about the treatment of Americans held inside the Tehran embassy, is believed to be based on information supplied by some of the 13 blacks and women who were released.

Pentagon officials said the aircraft carrier Kitty Hawk has arrived in the Arabian Sea "in the general vicinity" of another force headed by the carrier Midway. The two grroups are rerported to be carrying more than 135 planes.

The Socialist Workers Party and the National Emergency Committee, in one action, and the American Civil Liberties Union, in a separate action, filed lawsuits seeking to halt the new requirement that Iranian students in the United States prove they are attending school or face deportation.

Among the contentions of the suits were that the Nov. 13 Justice Department order violated the rights of Iranian students and violated the administrative procedures required by law. Of about 50,000 Iranian students in this country, some 26,000 reported to immigration offices in the first two weeks of the new program, according to the Immigration and Naturalization Service.

About 3,500 of those reporting were found to be deportable, and the documents of 1,900 others are still under study, INS said.

The American Bar Association and, in a separate statement, a group of 19 prominent jurists from several countries condemned the holding of diplomatic personnel as hostages as a violation of international law. The statements asked for release of the hostages.

The State Department reported that Vance has canceled plans to visit Romania, Yugoslavia and West Berlin next week, when he will be in Europe for an important NATO meeting. Vance is to leave next Tuesday night for the NATO meeting, which is expected to give formal approval to deployment of new medium-range missiles in Western Europe. CAPTION: Picture, Deposed shah of Iran Mohammad Reza Pahlavi talks with television personality Barbara Walters in this photograph taken Thanksgiving Day in his hospital room. Copyright, (c) 1979, ABC News