Senior American diplomats dealing with Central America held strategy meetings at the State Department yesterday in the first stage of an administration effort to determine whether a regional peace initiative can resolve the tensions between Nicaragua and its neighbors.

The meetings were part of a cautious, step-by-step approach laid out by the department last Friday to assess the strengths and weaknesses of the plan adopted recently in Guatemala by the presidents of Nicaragua, Honduras, Costa Rica, El Salvador and Guatemala.

The aim is to test whether the Central American plan contains sufficient safeguards against Cuban and Soviet influence over Nicaragua's Sandinista government for the United States to phase out its military support of Nicaragua's contras and join the search for a negotiated peace.

The question of what approach the United States should take toward the Guatemala initiative has caused divisions within the administration that last week led Philip C. Habib to resign as President Reagan's special envoy for Central America. Habib had wanted to go to the region and engage the United States in the talks among the five countries.

He was overruled by a White House decision to avoid direct discussions with Nicaragua for the time being and take a more wary, arms-length approach to the Guatemala initiative until it is clear whether such talks can be made to accommodate Washington's concerns satisfactorily.

The administration's continuing mistrust of the Sandinistas was underscored yesterday when State Department spokeswoman Phyllis Oakley began the daily news briefing with a statement condemning Nicaragua's violent suppression of weekend demonstrations in Managua, the capital. She said that events there "call into serious question the Sandinista government's willingness to fulfill the commitments made by President {Daniel} Ortega to democratize Nicaragua."

Yesterday's meetings brought together American ambassadors from the region, defense officials and policymakers dealing with Central America. Department officials described the sessions as an exchange of views and information intended to result in instructions for the ambassadors about the views the administration wants conveyed to the Central American governments and ways to influence them to accommodate U.S. concerns in their negotiations.

The U.S. ambassadors are to return to Central America and begin contacts with their host governments prior to a meeting in the Salvadoran capital later this week, where the five countries' foreign ministers will set the stage for their negotiations.