President Carter, responding to assorted calls for a diplomatic settlement of the Afghanistan crisis, has proposed that the United States and the Soviet Union join other nations to guarantee Afghanistan's neutrality, administration officials disclosed yesterday.

In a letter sent Monday to Yugoslavia's President Tito, Carter asserted that, "with a prompt withdrawal of all Soviet troops from Afghanistan, the United States would be willing to join with Afghanistan's neighbors in a guarantee of true neutrality and non-interference in Afghanistan's internal affairs," according to the officials.

While the president's letter was sent to Tito, it also represented in part the first American response to last week's speech on the Afghan crisis by Soviet President Leonid Brezhnev.

In the speech to a Kremlim political gathering, Brezhnev demanded an international "guarantee" by the United States and other nations to end alleged subversion in Afghanistan, and said the Soviets are prepared to begin withdrawing their troops "as soon as all forms of outside interference directed against Afghanistan" are terminated.

Carter replied indirectly, in his letter to Tito, that the United States has not interfered in Afghanistan's affairs, and that as soon as the Soviet troops were withdrawn, the United States is prepared to join in a "guarantee" of Afghan neutrality.

The administration decision to disclose aspects of the president's letter to Tito appeared to be, in part, an initial, cautionary exploration of a possible diplomatic resolution of what Carter has characterized as the greatest threat to peace since World War II.

It also appeared to be an effort to deflect any criticism that the United States was ignoring the possibility of a negotiated settlement in its desire to "punish" the Soviets for their aggression.

The president's call for a guarantee of Afghanistan's neturality closely resembled a proposal made last week by the nine European Common Market countries, which agreed to offer a guarantee of Afghanistan's neutrality if Soviet troops were withdrawn.

A number of European governments, led by France, are known to believe that the United States has placed too much emphasis on punitive measures directed against the Soviets, for example the proposed Olympic boycott, and not enough on the possibility of a diplomatic settlement.

Secretary of State Cyrus R. Vance discussed Brezhnev's speech and the neutralization proposal with European leaders last week and, according to U.S. officials, told them the United States favors pursuing any approach that might lead to a negotiated settlement.

Tito, who is gravely ill, sent letters last week to Carter and Brezhnev appealing for a renewal of efforts to revive detente between the two superpowers. The text of what was described as the president's "lengthy" reply was not made public, but yesterday reporters were offered a "characterization" of the contents by a senior administration official on condition that he not be identified.

According to the official, the president "reaffirmed his personal commitment and that of the United States to a truly universal and reciprocal detente" but stated that the Soviet invasion of Afghanistan "has dealt a severe blow to the process of detente."

The official said Carter "expressed concern that the Soviet Union tends increasingly to define detente in a way that threatens the interests of the international community and in particular the interests of nonaligned countries." Moreover, he said, the president "emphasized that there cannot be genuine detente without respect for the independence and territorial integrity of all countries, and pointed out that these principles are threatened by the Soviet invasion of Afghanistan."

"The president reiterated that the United States supports the restoration of a neutral, nonaligned Afghan government -- a government that is responsive to the wishes of the Afghan people," the official said. "He stated we are prepared to support efforts by the international community to that end."

The administration initially was wary of the Brezhnev speech and uncertain of how to read its significance. While the Carter letter to Tito suggested a willingness to explore the neutrality proposal as a way to end the crisis, there were no signs yesterday that the administration expects such an approach to be successful in the short run.

The president's proposal is based on a Soviet troop withdrawal being the first step in the process, and officials said there is nothing to indicate the Soviets are planning to begin withdrawing troops.

In another development, Carter confirmed in the text of an interview released yesterday that the United States has offers from both Israel and Egypt for the use of "facilities" in those countries by military units in times of crisis. He said the United Staes is developing similar arrangements with other countries in the region, among them Kenya, Oman and Somalia.