The Nicaraguan government and an Indian rebel group agreed today to avoid staging offensive military actions against each other. It was the first accord between the Sandinistas and any of the various guerrilla organizations battling them.

Brooklyn Rivera, leader of the Indian group Misurasata, accepted the deal on the condition that the government resume providing medicine and food to Indians on Nicaragua's Caribbean coast, and that it allow international relief organizations to deliver aid there. Until now, the government effectively has blocked the supply of such aid because of Indian guerrilla activity.

From the Sandinistas' point of view, the accord was timed for impact on the U.S. congressional debate over President Reagan's request for $14 million in aid to Nicaraguan antigovernment guerrilla groups other than Misurasata.

A Nicaraguan official acknowledged privately that this was "an element" in the government's negotiating strategy. Nevertheless, the five-point communique marked the first substantive agreement between the Sandinistas and Misurasata since Rivera became the first Nicaraguan rebel leader to enter peace talks with the government in December.

"I think that the American legislators will have to take into account the concrete advances that the Sandinista government and Misurasata have achieved," Deputy Interior Minister Luis Carrion said at a news conference. He and Rivera signed the document after two days of talks at the Foreign Ministry .

The accord "demonstrates that the Nicaraguan government has the political will to seek a negotiated solution," Carrion said. The deal here came on the heels of a proposal yesterday by Nicaraguan President Daniel Ortega to call a cease-fire with all antigovernment guerrilla groups if the United States halted all aid to the rebels and resumed direct negotiations with the Sandinista government.

Misurasata is the smaller of two rebel organizations embracing Miskito, Sumo and Rama Indians from Nicaragua's isolated, jungle-covered eastern coast. The larger Indian rebel group, called Misura, has called Rivera a traitor for entering the peace talks.

Rivera declined to say how many guerrillas he commands. Estimates range from 500 to 1,000. Misura is believed to have about 2,000.

Neither Carrion nor Rivera called the agreement a cease-fire, but the communique committed both sides "to avoid armed offensive actions" between them. Fighting between the government and Misurasata has been sporadic anyway recently.

Rivera said that a formal cease-fire could be reached in future talks if the government respects its promise to allow delivery of aid to the Indians. The two sides agreed to hold further talks May 25-26 in Bogota, Colombia.

"We want to test the supposed good faith of the Nicaraguan government," Rivera said.

Despite the agreement, no progress was reported on the fundamental issues dividing the government and Misurasata. These include the Indians' demands that the government recognize their rights, as indigenous peoples, to land and minerals, and to some form of self-government in a territory still to be delineated in eastern Nicaragua.