Venezuelan President Luis Herrera Campins, who has been a strong backer of the Reagan administration on El Salvador, criticized recent U.S. policy in Central America today and said Washington "should make an effort to comprehend" Latin America's problems "in order to act in a realistic way."

Herrera also said that following elections scheduled for Sunday in El Salvador his Christian Democratic government would reevaluate its own policy there, no matter who the victor was. He did not rule out possible Venezuelan support for talks with El Salvador's left-wing forces.

Herrera made his remarks in an interview in the presidential palace here one day after releasing a letter he received from the leadership of the antigovernment guerrillas in El Salvador. The letter, signed by the five military commanders of the Farabundo Marti Liberation Front, said Venezuela could make a "decisive" contribution to a "just political solution" in El Salvador and called on Herrera to help bring about the comprehensive negotiations the guerrillas have proposed.

Herrera, who read parts of the letter on Venezuelan television last night, answered the guerrilla leadership with a new endorsement of the Salvadoran elections, which the guerrillas and their political allies are boycotting on the ground that the elections would be unfair and fraudulent in the country's current climate of violence. But he said today, "I am awaiting the electoral results in order to establish our attitude toward the possibilities that exist" for resolutions of the country's crisis.

The United States and the Salvadoran government steadfastly have rejected suggestions of talks with the guerrillas, arguing that they should take their case to the Salvadoran people through the elections rather than bypassing the ballot box for the bargaining table.

Venezuela has provided more than $100 million in economic aid to the Salvadoran government and Herrera called the elections "a democratic triumph against the threat of subversion." He expressed strong hopes that the party of his fellow Christian Democrat and personal friend, Salvadoran President Jose Napoleon Duarte, would win.

Although it has joined in U.S. support of Duarte and the Salvadoran elections, Venezuela long has differed with Washington on several key Central American issues, most importantly the Sandinista government in Nicaragua. Last year, the Reagan administration suspended U.S. aid to Nicaragua to protest Cuban influence there and Sandinista support for the Salvadoran guerrillas.

Venezuela, whose support of the Sandinistas was instrumental in their 1979 victory over dictator Anastasio Somoza, has continued to support and send economic aid to the Sandinista government. Herrera reiterated that backing today, saying that Venezuela would continue its ties to Nicaragua "while there is a possibility that they will realize their pluralistic projects."

Herrera also responded sharply to recent rhetorical attacks by the Reagan administration on Nicaragua and reported plans for CIA-backed, covert, paramilitary operations to interrupt supply lines to the Salvadoran guerrillas by disrupting the Nicaraguan economy.

"The language of the threat," said Herrera, "is very far from being the answer to the situation in Central America and the Caribbean. We reject all armed intrusion in the area."

Herrera said that the United States "has a great potential" to help Central America but added that "it does not have the same historical and economic roots as Central America and South America. The United States should make an effort to comprehend those factors in order to act in a realistic way," Herrera said, adding, "and they have to make that effort more intensely."

Among events that have annoyed the Venezuelan government were the recent NATO naval exercises in the Caribbean, about which Venezuela was not informed in advance. Venezuela protested the maneuvers in the Organization of American States, and Herrera said yesterday that the NATO countries should be looking for "peace and not confrontation" in the Caribbean.

Although Herrera praised President Reagan's new Caribbean Basin initiative as a "political opening," he argued that the plan did not include enough aid for Central American and Caribbean countries.

"This is very little for the United States to give," Herrera said. "This is what we give every year to nine countries in Central America and the Caribbean," he said, referring to the joint Mexican-Venezuelan program of oil-import subsidies for countries in the region.

"If Mexico and Venezuela can give 350 million dollars a year," Herrera said, "the United States should be able to make a much bigger contribution."

Herrera's announcement that Venezuela will reevaluate its policy toward El Salvador after Sunday's election comes at a time of continuing criticism on the issue from the government's domestic political opposition. The social democratic chief opposition party in Venezuela, Democratic Action, has said that elections in El Salvador will not help the country and that Venezuela should support negotiations between the Duarte government and the left.

The letter received by Herrera from the guerrilla leaders, Democratic Action leader Simon Alberto Consalvi said today, "is another demonstration of the possibility of doing what should have happened a long time ago: a search for political negotiation between the various sectors of El Salvador."

Herrera refused to say today whether he would support or consider negotiations in El Salvador when the elections were over, and instead focused on his hopes that what he called "the people who believe in change" would win the election.

"Our information shows us the probable victory of the Christian Democrats," Herrera said, "despite the international campaign that has been orchestrated against President Duarte and the junta that in its basis could benefit the reactionary right."

Five other parties, all to the right of the Christian Democrats, are contesting the election.

"A victory by the Christian Democrats," said Herrera, "would simplify the matter greatly because it would guarantee the continuation of the social reforms started by the government."