Despite U.S. denials that any decisions have been made, the diplomatic signs yesterday began pointing toward the Egyptian-Israeli peace talks resuming here shortly under the mediation of Secretary of State Cyrus R. Vance.

That impression emerged from a day of confusing signals that included an Israeli diplomat's speculation about new talks in mid-month, a U.S. retort that such predictions were "jumping the gun" and an Egyptian call for Vance to decide the next step in getting the deadlocked negotiations moving again.

But, after sifting these contradictory developments, many diplomatic sources predicted that the Carter administration -- if it wants to break the impasse -- will have no choice other than to seize on the tentative willingness of the two sides to start talking again and schedule a new round of Washington negotiations.

Such a course would involve considerable risks, the source noted, since neither Israel nor Egypt seems wiling to modify the opposing demands that caused the peace talks to break down during Bance's Middle East shuttle mission last month.

However, the sources added, Washington's much-advertised fear of an erosion of support for a peace treaty in the two countries would appear to make a quick resumption of negotations imperative.

In addition, the sources said, for the talks to be effective they would have to be conducted at the level of foreign minister and defense minister.That, in turn, would require Vance to resume his role as mediator, and, for that reason, the sources said Washington would have to be the locale for any new negotiations.

This deductive scenario was first revealed by an Israeli diplomat at a meeting with reporters yesterday. The diplomat, who asked not to be identified, noted that both sides appeared willing to resume negotiations, and added: "We assume it will be here in mid-month because of Mr. Vance's calendar."

Reports of the diplomat's remarks drew a quick and emphatic reply from the State Department spokesman, Hodding Carter. He charged the diplomat with "jumping the gun," and, while conceding that the administration would like to see the talks resumed, Carter stressed, "There is no time set, there is no meeting set."

U.S. sources said privately that Carter's vehement retort was prompted, in part, by the fact that Egypt had not yet replied to U.S. suggestions about resuming the talks. As a result, the sources said, the State Department did not want to give Egypt the impression that Washington had decided on a specific course and that the Israelis had special knowledge of it.

In addition, the sources added, the United States is troubled by the fact that neither side seems willing to make significant concessions and wants to explore further the possibility of their giving some ground before scheduling new negotiations.

Carter refereed to that problem by saying: "The first thing you want to know is what is feasible to do, and for that, you have to have something back from the parties themselves... How you do it, when you do it, where you do it, are matters which we are trying to work out with the parties. It hasn't been resolved."

Later in the day, though, the Egyptian cabinet concluded a six-hour meeting by aqnnouncing that it is prepared to resume efforts toward a peace treaty. In announcing the decision, Prime Minister Mustafa Khalil said Egypt's position would be conveyed to Vance within the next two days, and added that it then would be up to Vance to decide how to get contact between the two countries resumed.

In stating their position, the Egyptians reiterated their demand for a timetable linking the proposed treaty to separate negotiations on establishing Palestinian autonomy in the Israeli-occupied West Bank and Gaza Strip. The cabinet also insisted anew that any peace treaty with Israel must not supersede Gypt's defense treaties with other Arab states.

These are the principal issues that have caused the impasse in the negotiations. Israel, while saying it is willing to negotate on Palestinian autonomy, has refused to accept a timetable and has insisted on a clear understanding that the peace treaty take precedence over Egypt's other obligations.