Secretary of State George Shultz leaves Monday on a nine-nation Latin American trip designed to highlight U.S. efforts to promote democracy and to work on Washington's biggest regional problem, Nicaragua.

Shultz's first stop, on Monday, will be in Central America, which U.S. officials admit has provided their most nagging foreign policy headaches.Congress has limited the administration's leeway for action toward the leftist government in Nicaragua by refusing to give the U.S.-backed Contra rebels further military aid.

White House efforts to oust Panamanian strongman Manuel Noriega have come to nothing, although U.S. officials say President Reagan recently authorized unspecified new covert efforts to force Noriega out.

During a stop in Guatemala City on Monday, Shultz will hold his second round of talks on Central American issues in four weeks with the foreign ministers of Guatemala, Honduras, El Salvador and Costa Rica.

A senior administration official said these talks will focus on how to pressure Managua to comply with agreements signed with Central American leaders and Contra rebels to make democratic reforms in Nicaragua.

In early July the Sandinista government staged a crackdown on opposition forces, jailing politicians, temporarily closing a newspaper, violently breaking up an opposition demonstration and expelling the U.S. ambassador.

The Sandinista moves followed a breakdown of peace talks with the Contra rebels in early June. But a ceasefire has been in force since April.

Despite the bleak prospects for a renewal of talks, the Congress has been reluctant to renew military aid to the Contras, forcing the Reagan administration to resort to diplomatic pressure on Nicaragua.

The administration official said the recent wave of repression increased the urgency of bringing pressure on the Sandinistas.

This source, who asked not to be identified, said the pressure Washington is seeking could be either a statement of principles by the foreign ministers or an attempt to get Western European nations to use their influence on Nicaragua.

From Guatemala, Shultz will fly to Buenos Aires for talks on economic development and Argentina's huge debt to international banks.