Cuban President Fidel Castro, whose troops helped Ethiopia to victory in the Ogaden war, was reported yesterday to have come out for a negotiated settlement in Ethiopia's other war, in Eritrea, rather than commit his combat forces in massive numbers there.

Ethiopia's leader, Col. Mengistu Haile Mariam, is currently on a visit to Havana, where he has made public calls for further Cuban support in an allout war against the secessionists in strategic Eritrea Province. Castro however, has avoided such a public commitment.

Diplomatic sources in Havana have reported that representatives of the Eritrean rebels are also visiting Cuba and may be negotiating with Mengistu, using Castro as mediator. This report could not be confirmed independently.

Castros' call for negotiations was reported by Palestinian sources in Beirut. According to Reuter news agency, these sources said Castro outlined his views to George Habash, secretary general of the Popular Front for the Liberation of Palestine, who is also in Havana.

Despite recent reports including statements by a White House official, that Cuban pilots, advisers and even combat units have appeared on the Eritrean front, some State Department officials have maintained that Cuba wants to avoid involvemetn there.

According to U.S. estimates, 17,000 Cuban troops are still in Ethiopia although the war against Somali insurgents in the Ogaden area ended two months ago. State Department officials insisted yesterday that there was no evidence yet of any Cuban troops having engaged in combat in Eritrea.

Cuba has long supported Marxist guerrillas among the Eritrean seccessionists and it maintains close ties with such Arab supporters of the Eritreans as Syria and Algeria.

Mengistu sought to lingk Cuba to his cause in Eritrea during a ceremony in which Castro awarded him the Order of Playa Giron - the Bay of Pigs. Mengistu thanked him for the critical support in the Ogaden and added:

"I also have confidence that the revolutionary Cuban people and progressive forces of the whole world will be on our saide in this struggle" for Eritrea.

Neither at that time nor in later public appearances did Castro indicate he would provide such support.

At a rally yesterday, Castro specified that Cuban troops would gain intervene "if another invasion of Ethriopia occurs." In the Ogaden, Somali forces did cross Ethiopia's internationally accepted border. While the origins of the Eritrea conflict are complex, they in no sense involve an invasion. Seccessionists have seized control of virtually all of the province but Ethiopia troops still hold the two main cities.

Castro's discomfort in trying not to offend either side in what ssentially is a civil war became obvious when the Cuban leader pledged at another point to support "the integrity of the Ethiopian state." He ven noted approvingly that Abraham Lincoln had to use the force of arms to maintain the United States.

According to special correspondent Lionel Martin in Havana, however, Castro insisted upon a peaceful solution in Eritrea and even laid down some negotiating terms - which lacked specifics.

Mengistu replied with another call for the Cubans to be at his side in Eritrea, saying that while he was seeking a peaceful solution the secessionists were not interested. We will "destroy this counter-conspiracy," he said.