Top U.S. and Mexican officials finished two days of high-level talks here today apparently little closer on the key issue of Central America, although both sides agreed in a joint statement to "promote processes of dialogue and negotiation" in the region.

Mexico, which supports the Sandinista government of Nicaragua and has pushed for a negotiated settlement of the conflicts in the region, has just begun a new diplomatic initiative on Central America involving Panama, Venezuela and Colombia.

Foreign Minister Bernardo Sepulveda is to go to Panama Wednesday to continue talks. Secretary of State George P. Shultz stressed at the airport that the "key is the fact that all five Central American countries will be there in Panama which to my mind is a recognition of the basic fact that the issues are fundamentally regional."

Later, during a refueling stop in Tampico on his return flight to Washington, Shultz told reporters that the question of arms flow was one of the subjects being discussed by Sepulveda and the other regional governments. Shultz said, "Certainly one of the things he does see as important is the cessation of arms flows from one country to another. That's really what's taking place from Cuba and Nicaragua to El Salvador."

The U.S. position is that Cuba and Nicaragua are responsible for instability in the region, and that the problems in Central America can only be solved on a regional basis. Shultz said, "I've explained our analysis of the situation and the things we're trying to do to help bring about security for the region" in talks with both the foreign minister and Mexican President Miguel de la Madrid Hurtado, with whom he said he had spent considerable time.

Earlier, a senior administration official said that Shultz had made clear to the Mexicans that the United States would continue its involvement in the area until a solution is reached.

Sepulveda said pointedly at the airport that Mexico is "seeking medium-term solutions to the problems of Central America, but we have to undertake" the initial steps toward such a solution with "urgency." He added, "We have to generate a peaceful mechanism in Central America and that cannot be done on a short-term basis."

Earlier, Treasury Secretary Donald T. Regan told reporters that the slump in the Mexican economy since the nation's near default last August had cost about 200,000 U.S. jobs through lost exports and was likely to continue this year. Commerce Secretary Malcolm Baldrige also predicted that U.S. exports to Mexico would fall again this year after last year's $6 billion decline.

Administration officials in Washington have said that the economic and financial problems of Third World nations will likely reduce U.S. growth by about 1 percent this year, as debtor nations curb their spending overseas.

Regan said the United States is "trying to see what we can do to encourage more trade" with Mexico, its third largest trading partner. While the United States has suffered from a decline in exports to Mexico, particularly in the border areas of the southwest where economic ties are very strong, Mexico also complains that it needs easier access to U.S. markets if it is to recover economically.

Regan indicated that if Mexico needs more cash later this year the U.S. government is likely to tie its financial aid to purchases of U.S. goods.

Mexico has pushed hard during the talks for a bilateral trade agreement with the United States that would enable Mexican industries and agriculture to export more easily. Baldrige has agreed to resume active discussions of bilateral trade matters.

Mexico is following a strict austerity program designed by the International Monetary Fund. Regan said the Mexicans were "ahead of many Latin American nations in getting their house in order . . . they are making a very sincere effort to continue despite the hardships that they know are hurting their people." The Mexicans are "struggling with the problem of very high and rising unemployment," he said.