Prime Minister Shimon Peres of Israel appealed to Jordan today to end their 37-year state of war and enter direct peace talks this year, with the United Nations taking the initiative to bring the two sides together.

"I invite this organization," said Peres, "to depart from the tired and timid norm and to fulfill its destiny . . . by ushering the parties to the conflict into a new diplomatic initiative."

Peres, one of more than 60 kings, presidents and prime ministers gathering in New York to celebrate the United Nations' 40th anniversary on Thursday, departed from recent Israeli policy by hinting at a U.N. role as an "international forum" that would help launch and support the peace process. This moved Israel closer to Jordanian King Hussein's demand for an international conference that would act as an umbrella for negotiations.

Jordanian Ambassador Abdullah Salah joined in the traditional boycott of the Israeli speech by leaving the assembly chamber along with all other Arabs, except for the Egyptians. He commented afterward, however, that his government was studying and analyzing Peres' remarks and giving them "careful consideration."

Egyptian Ambassador Ahmed Khalil called the Peres speech "a good start to keep the momentum going in the peace process." He said that Peres was "trying not to slam doors and had shown a commendable change in Israeli's attitude toward the peace process that made his proposal "worth asking more questions about."

Nowhere did Peres explicitly rule out participation by the Palestine Liberation Organization. A PLO role was a condition for talks as set by Hussein. Peres made only an oblique reference to "PLO terrorism," focusing on a call for the Palestinian people to renounce belligerency and talk peace with Israel."

The negotiations, said Peres, "may be initiated with the support of an international forum as agreed upon by the negotiating states," but "negotiations between Israel and Jordan are to be conducted between an Israeli delegation on one hand and a Jordanian-Palestinian or Jordanian delegation on the other." The latter, he added, must "represent peace, not terror."

Peres suggested the talks could be broadened beyond the base of Security Council Resolutions 242 and 338, which outline a framework for a Middle East settlement but make no reference to the Palestinians. They could "deal with the demarcation of boundaries as well as the resolution of the Palestinian problem," he said.

Peres was similarly conciliatory and imprecise in his references to the nature of the "international forum" that could initiate and support the peace process. He said the permanent members of the Security Council -- the United States, the Soviet Union, Britain, France and China -- could be involved but cautioned that Israel's position was that those that do not have diplomatic relations with Israel -- Moscow and Peking -- "exclude themselves from such a role."

Peres said, "working groups should be convened within 30 days to agree upon the agenda, the procedures and the nature of "international support," Peres said.

Privately, Jordanian officials suggested that the proposals would depend on the spirit with which the ideas in the speech are pursued. The officials acknowledged that there was a shift in Israel's acceptance of an international forum and its willingness to go beyond the limitations of Resolution 242. But they cautioned that the offer to attend an international forum was carefully qualified by Peres, and there was no clear sign of Israel's willingness to permit PLO representation in the negotiations -- a necessary condition, as one Jordanian said, "whether we like it or not."

But PLO representative Zehdi Labib Terzi dismissed the Israeli suggestion as a speech "directed at the U.S. audience to tell them Israel wants peace." He said that Peres should realize that Hussein cannot move without the PLO.

U.S. and other western officials, however, saw the speech as encouraging further movement.

In an earlier address, Nicaraguan President Daniel Ortega challenged President Reagan to "cease his policies of aggression" and tell the United Nations if Washington "is ready to stop the war against Nicaragua and declare peace."

Ortega said Nicaragua, for its part, "will suspend the state of emergency we have been forced to impose due to those acts of aggression as of the very moment when those aggressions effectively cease."