The Carter administration and key senators yesterday searched for a way to mute the impact of the controversial "DeConcini reservation" to the first Panama Canal treaty without losing senators' votes for the canal treaties.

During a hectic day of rumors and maneuvers, it became known that Panamanian officials objected bitterly to the reservation before it was passed, and that its acceptance by President Carter nearly provoked Panama's leader, Gen. Omar Torrijos, to renounce the treaties.

U. S. officials, including the president, knew that Panama might well reject the reservation at the time they decided to accept it in order to win key votes in the Senate.

The reservation, introduced by Sen. Dennis DeConcini (D-Ariz.), asserts a U. S. right to intervene military in Panama at any time to keep the canal open. DeConcini and at least one other senator, Paul Hatfield (D-Mont.), said they could vote for the first treaty only if it included this reservation, and their votes were crucial in the 68-to-82 Senate vote to approve the treaty.

Yesterday, administration officials began courting DeConcini's staff in preparation for an attempt to somehow clarify the meaning of the reservation in order to placate Panamanian opinion, which reportedly has been inflamed over this issue in recent days.

DeConcini was flying to Washington from Arizona late last night and is scheduled to meet with Carter today or tomorrow.

Sen. Frank Church (D-Idaho), floor manager for the canal treaties, yesterday implored the Senate to find a way to "reassure the people of Panama" that the United States did not want to abandon its longstanding adherence to the principle of nonintervention in other countries' affairs.

Obviously aware that some senators' votes for the second canal treaty might be lost if an attempt were made to dilute the DeConcini reservation. Church insisted that no dilution was necessary. The problem, he contended, "is not really one of substance," but rather comes from a Panamanian misinterpretation of what the Senate was trying to do when it adopted the reservation.

Church said the reservation just made clear the essential meaning of the treaty, guaranteeing that both Panama and the United States had the right to defend the canal's neutrality. The problem, he said was that Panamanians now believe that the reservation "is intended to humiliate them as a nation by delegating to the United States the ultimate right to govern their affairs."

Church did not make a specific recommendation but he implied that the Senate should adopt some new resolution or ammendment to the second treaty reasserting U. S. acceptance of the principle of noninterference.

But that gambit could only work if all the senators involved agreed with Church that Panama's present concern is based on a misunderstanding, and that the DeConcini reservation did not suggest any intrusion on Panama's sovereign rights.

But an aide to DeConcini said yesterday that in some circumstances it might prove impossible to intervene in Panama to keep the canal open without "treading on Panamanian soverignty."

The DeConcini reservation, the aide sad, "does represent perhaps a departure" from the historic U. S. acceptance of the principle of noninterference, "but it represents a departure in a very unique case" - that is, to protect the American-built canal.

Administration officials and several senators expressed uncertainty yesterday about whether DeConcini could be persuaded to accept some gesture to Panama to soften the impact of his reservation. At the moment, DeConcini intends to propose another reservation to the second canal treaty that could further inflame Panamanian opinion.

This one would say that U. S. forces stationed in Panama until 2000 would retained the right to act independently to defend the canal.

New details on the history of the first DeConcini reservation emerged yesterday and offered a new glimpse of the administration's difficulties in winning Senate approval of the treaties.

The story began in February, when DeConcini proposed amending the first treaty (guaranteeing the canal's neutrality after 2000) with language similar to that of his reservation. Senate leaders and administration sources pressed him not to make this an amendment, feoring that such a change in the treaty text might force Panama to hold a new plebiscite ot retify the treaties.

At the last moment, DeConcini agreed, then proceeded with is plan to offer the reservation. An aide to the senator said yesterday that the administration and Senate leaders probably "were kidding themselves" that the Panamanians would be markedly less concerned with reservations than with formal amendments. (Under international law the two apparently have equal force.)

The State Department proposed an altered version of DeConcini's text, but only at the last minute, and the senator rejected it. On March 14 he submitted a final version that was more explicit that any earlier draft in claiming a U. S. right to intervene militarily in Paname after 2000.

An aide to the senator said last night that DeConcini expected the administration to propose a time limit on this right to restrict its applicability to the territory of what is now the Canal Zone, both of which DeConcini might have accepted. But the administration made no such proposals.

Unbeknownst to DeConcini, two U. S. diplomats presented his draft reservation to senior Panamanian officials on March 14 in Panama City. The officials reacted strongly and negatively, and the diplomats sent two telegrams to Washington that day saying the Pananamanians regarded the reservation as unacceptable, according to authoritative sources.

On the morning of the 15th, Carter met with DeConcini at the White House and accepted his reservation.

When Torrijos learned this, an informed source said, he was furious. He scheduled a television speech for 6 p.m. that night, the source said, and prepared to denounce the reservation in terms that could have scuttled the treaties.

Before the speech was made, Carter talked to him by telephone, apparently calming him. Later that day the two exchanged letters. Torrijos' said Panama would reserve judgment on the reservations until the Senate completed action on both treaties.

In another development yesterday, treaty opponents in the Senate circulated a document purporting to be a Panamanian diplomatic memorandum on a meeting between Panama's ambassodor to Washington, Gabriel Lewis, and Frank Moore, chief of Carter's congressional liaison staff.

According to this document, the Panamanians understood Moore to promise last Wednesday that the administration would soon produce a resolution for Senate consideration that would "neutralize" the DeConcini reservation.

Moore last night issued a statement calling this version of the meeting inaccurate.

The Senate yesterday voted 49 to 40 to table an amendment by Sen. Bob Dole (R-Kan.) to delete a provision of the second treaty committing the United States to build any future cancal in Panama.