Central American nations appeared to take a step toward serious negotiations on that region's conflicts Thursday. Honduras, Guatemala, El Salvador, Costa Rica, and Nicaragua agreed to try to:
* Freeze arms imports.
* Reduce the size of their armies and the number of foreign military advisers. This presumably means barring new Cuban advisers in Nicaragua and American advisers in El Salvador and Honduras.
* Bar use of their territories as staging grounds for guerrilla raids against neighbors.
* Prevent terrorism and subversion in the region.
The agreement, announced Thursday at the United Nations, came through the mediation efforts of the Contadora Group, which Mexico, Venezuela, Colombia, and Panama formed to try to resolve the Central American conflicts.
The declaration sets the groundwork for future negotiations between the Central American nations. This agreement was subject to intense negotiations until the last minute - with Honduras and El Salvador, on the one hand, and Nicaragua on the other, distrusting each other's intentions.
Colombia's President Belisario Betancur describes the agreement as ''a major step toward restoring peace in Central America.''
But whether this agreement will stop Central America from sliding further toward military confrontation is ''open to question,'' says an observer here.
US diplomats say they hope ''it will work out.'' But State Department officials do not see the declaration as a major step forward. They note that military activity in the region is escalating and that Salvadorean rebels say talks with Salvadorean officials are not moving ahead. The officials point out that the declaration announced Thursday for the most part formalizes an agreement reached in Panama in September.
The US intends to keep its military and paramilitary options open, and ''not allow the military balance to shift in favor of the pro-Soviet forces in the region,'' says a US official.
Western European countries and most Latin American countries have come out publically in favor of the Contadora mediation efforts.
Thursday's declaration was handed by the Contadora foreign ministers to UN Secretary-General Javier Perez de Cuellar, who is expected to report on it to the Security Council.
The agreement also calls for the Central American nations to agree to discuss joint economic development plans, respect of human rights, and a pledge to hold democratic elections.