The United States has dismissed intensified appeals from leftist rebels and other Latin American leaders for negotiations to end El Salvador's bloody two-year-old civil war as "repackaging of previous proposals."

The Salvadoran government last week also rejected the latest offer of the Salvadoran opposition Democratic Revolutionary Front, and its guerrilla counterpart the Farabundo Marti National Liberation Front, which called for negotiations "without preconditions" and mentioned that elections are "an important mechanism" to ensure widespread participation. The offer was conveyed last Wednesday to the U.N. General Assembly by Nicaraguan leader Daniel Ortega.

A U.S. government official, who asked not to be identified by name, said the United States is constantly "on the lookout" for new proposals, but said the offer transmitted last week by Nicaragua, while mentioning elections, still calls for restructuring of the Salvadoran armed forces as part of the agenda for negotiations to end the conflict, which has claimed about 30,000 lives in a country of 5 million people.

Although the civilian component of the Salvadoran junta has in the past shown a willingness to set terms for negotiations, for most of this year it has joined that government's armed forces and the United States in rejecting leftist appeals as ploys to gain time for a military victory.

The U.S. position has been to support the ruling military-civilian junta's call for the opposition to lay down its arms and participate in elections scheduled for next March. The United States has embraced the electoral solution as one way to demonstrate that the present government has popular support and to isolate the far leftist groups within the opposition coalition.

U.S. government officials reportedly feel that the opposition groups have constantly repackaged their offers to parry civilian junta president Jose Napoleon Duarte's insistence that the conflict be settled through elections.

Opposition groups, however, have argued that the ruling junta has used the call for elections as ploy to avoid substantive discussions and to avoid any negotiations that would affect the structure of the armed forces.

A prominent exile, Col. Adolfo Arnoldo Majano, Monday joined those who have criticized the elections proposal as unworkable. Majano, who was a leader of the Oct. 15, 1979, coup which ousted Gen. Carlos Humberto Romero and led to the current junta, and himself was a junta member before being forced out by other military leaders in January, said in a statement that the "unilateral imposition of an electoral process . . . could lead to even more internal discord."

Majano, in a separate interview yesterday, also accused the present military leadership of "betraying" the spirit of the Oct. 15 coup, which he said was undertaken specifically to rectify ongoing abuses of human rights. Those abuses, he said, have, if anything, gotten worse, since the coup.

Monday, in his first statement since he was released from prison and went into exile last March, Majano said the present military leadership is responsible for the violence in the country and that those leaders have damaged the reputation of the armed forces as an institution.

"Elections are inappropriate in the current conditions," Majano said, "because the appropriate climate to carry them out does not exist; there is a lack of confidence of the people in this political resource owing to past . . . scandalous electoral frauds."