Fred C. Ikle, the third-ranking official in the Defense Department, last night called for a military victory in Central America, saying negotiations alone cannot resolve current conflicts there.

Ikle, undersecretary for policy, also suggested that lukewarm congressional support for President Reagan's program of economic and military aid could force the United States to deploy troops in the region, "as in Korea or West Germany."

Ikle's remarks, prepared for delivery to the Baltimore Council on Foreign Affairs, and last week's visit to the area by Defense Secretary Caspar W. Weinberger renew the administration's bid for congressional support for increased U.S. involvement in El Salvador, Nicaragua and Honduras.

In addition to seeking more military and economic aid for El Salvador and rightist insurgents in Nicaragua, the Reagan administration has decided to increase by as many as 11 the number of U.S. military personnel in El Salvador, informally limited until now to 55, officials said yesterday.

Weinberger said in an interview last week that he expects Guatemalan troops to be trained at a camp in Honduras operated by U.S. Green Berets, although there are no specific plans to do so.

Congress has refused to authorize military aid to Guatemala because of alleged human rights violations by its military government.

Ikle, casting doubt on the potential effectiveness of diplomacy in the region, said some of the leftist guerrillas fighting the Salvadoran government will never negotiate seriously.

"The hard core among the insurgents will never settle for a fair democratic process," he said. "We can no more negotiate an acceptable political solution with these people than the social democrats in revolutionary Russia could have talked Lenin into giving up totalitarian Bolshevism.

"Let me make this clear to you," Ikle continued, "we do not seek a military defeat for our friends. We do not seek a military stalemate. We seek victory for the forces of democracy."

Ikle said victory has two components, "defeating militarily" guerrillas who will not accept democracy and "establishing an adequate internal system for justice and personal security."

Ikle accused Congress of "crippling the president's military assistance program" and leading to a policy of "protracted failure." Last year, Congress provided about half the military aid Reagan requested for El Salvador, and the House has voted to cut off covert aid to guerrillas fighting the Sandinista government of Nicaragua.

Ikle urged continuation of covert aid to "democratic resistance forces in Nicaragua." Any other action, he said, "would turn Nicaragua into a sanctuary from which the nations of Central America could be safely attacked, but in which U.S.-supported forces could not operate."

A strong and unthreatened Nicaragua, in turn, could force the United States to place troops in neighboring countries, "as in Korea and West Germany," Ikle said. "Clearly, we must prevent such a partition of Central America."

Rep. Clarence D. Long (D-Md.), chairman of the House Appropriations foreign operations subcommittee, said Ikle's speech reflects the failure of administration policy in Central America.

"Now they perceive the policy as not working very well; they're nearing an election, and they want someone to blame it on," Long said.

Gino Lofredo, director of the Commission on U.S.-Interamerican Relations, condemned Ikle's mention of an East-West partition of Central America.

"This is the first reference to the Koreanization of Central America; it's no longer the Vietnamization. It takes three weeks to set something like that up and three months to dismantle it," Lofredo said.

He said his group is composed largely of former Carter administration officials and congressional aides with interest in Central America.

Congressional sources said Reagan has decided to exempt the 11-person military group in the U.S. Embassy in San Salvador from his self- imposed limit of 55 trainers in the country.

The decision, being discussed with congressional leaders, represents a compromise between those who wanted a substantial increase in the number of advisers and those who fear the political fallout from such an increase.

Weinberger supports exemption of the embassy military group from the self-imposed limit. "Some call it a self-inflicted wound," he said to U.S. personnel in El Salvador last week.

"There is some desire to adhere to the limit ," Weinberger told advisers and embassy personnel, "but there certainly isn't any desire to make your job infinitely more difficult by counting every American who comes in here."

The military group, a version of which exists in most U.S. embassies, administers military aid and advises local armed forces. The trainers are more involved with educating Salvadoran soldiers.