The United States wants negotiations between Nicaragua and four Central American neighbors to succeed and intends to help achieve a regional peace accord while protecting U.S. interests and President Reagan's commitment to Nicaragua's contras, a senior administration official said yesterday.

That, the official said, was the message given to U.S. ambassadors and other officials during a daylong meeting at the State Department Monday to discuss U.S. responses to the peace initiative recently adopted in Guatemala City by Nicaragua, El Salvador, Costa Rica, Honduras and Guatemala.

Since last week, reports have circulated that some ranking administration policymakers believe the Guatemala plan is tilted in favor of Nicaragua's leftist Sandinista government and could lead to abandonment of the contras. Internal administration disagreements over the best approach to take to the plan led last week to the resignation of Philip C. Habib as Reagan's special envoy for Central America.

"In the Monday meeting, we tried to clear up our overall policy," the senior official said, speaking on condition that he not be identified. "We thought it was crucial for our ambassadors and other diplomats in the region to make the foreign ministers of the four democratic countries understand before they meet {today in El Salvador} that we are not trying to subvert or undercut the agreement. That is not true. We want to make it work."

However, the official continued, "it also is necessary to clarify our goals and . . . what we regard as consistent with our national interest and our commitment to the democratic resistance in Nicaragua."

He said U.S. interests in the region are spelled out in a bipartisan peace plan backed by Reagan and House Speaker Jim Wright (D-Tex.): removal of Soviet, Cuban and other communist influence from Nicaragua, an end to Nicaragua's support of subversion in neighboring countries, and steps toward democracy in Nicaragua. Some administration officials are known to feel that, unlike the Wright-Reagan proposal, the Guatemala plan does not contain adequate provision for dealing with these points.

Regarding the contras, the official said, "We will not do anything that undercuts or weakens their position. There will be no concessions on that either militarily or symbolically. We will support them until there is an effective agreement being implemented in a way where they can go home to Nicaragua and live as free citizens."

The official said the United States seeks parallel and compensating concessions by both sides. "We think it would be a disaster for there to be irreversible movement on military reduction {affecting the contras} without corresponding movement on the political side," he said. "Otherwise the resistance would lose strength without making any political gains."

The official noted that U.S. military aid to the contras will run out on Sept. 30, while the Guatemala plan envisions a negotiating period through November. He added:

"If we assume . . . continued fighting between Sept. 30 and Nov. 30, . . . we will have to ask Congress for some way of dealing with that period. There is no question that the best way to destroy the Guatemala agreement is to ease off on the military pressure . . . . The worst outcome would be to get a good agreement which fails because we don't support the resistance to make the Sandinistas keep their promises."

In the Monday meeting, the official said, the Guatemala agreement was analyzed in terms of its potential effects on each of the five countries and in terms of specific issues. In addition to administration concern to safeguard U.S. interests, he said, there is a feeling here that several points in the Guatemala agreement are ambiguous and need to be defined much more precisely.

He mentioned as an example its call for cease-fires in regional guerrilla wars and asked whether that meant "a cease-fire in place, a cease-fire in cantonments or something else." Similarly, he noted, although the plan contains an amnesty provision, it does not spell out whether it would apply to "guerrilla fighters . . . who might lay down their arms, former guerrillas currently in jail or political prisoners in jail."