SAN SALVADOR, JUNE 4 -- Civil strife burst back into the capital city over the past week in a rapid succession of rebel sabotage actions, anti-American protests and mysterious attacks on leftist groups.

To many residents herethe violence in the last seven days stirred frightening memories of the early 1980s when street fighting and death-squad murders brought this small nation to the brink of revolution.

Although angry frustration with the three-year-old, U.S.-backed Christian Democratic government of President Jose Napoleon Duarte is widespread, he faces no danger of an urban revolt. After seven years of war, many Salvadorans feel the political alternatives to Duarte on the left and right are just as discredited, residents and political analysts said.

The events began May 28 when a noontime bomb blew off part of the roof of the offices of a left-wing committee of relatives of disappeared persons. Two employes at the committee, known as Comadres, were slightly injured.

The same day, two dozen refugees from another leftist group were occupying the city cathedral, demanding government permission to return to live in their home villages.

Last Friday about 100 refugees and Comadres members staged a raucous protest outside the U.S. Embassy, accusing the United States of encouraging the bombing. Hurling a barrage of rocks and at least one burning torch into the compound, they covered the embassy's looming concrete walls with graffiti.

On Saturday, witnesses said, two trucks of unidentified riflemen pulled up to the Nongovernmental Human Rights Commission, an independent group sympathetic to the leftist guerrillas fighting the government. After threatening to shoot the activists inside, the gunmen sped away when reporters arrived.

A well-known teachers' union leader was shot in the back at a demonstration Sunday at the gates of a penitentiary on the outskirts of the capital where political prisoners are held. Other union members whisked the wounded man, Julio Cesar Portillo, away. He has not appeared in public since.

Union members charged he was shot by prison guards. The police countered that the bullets had come from within the crowd of protesters.

Sunday was also the start of a three-day traffic halt ordered by the Marxist guerrillas of the Farabundo Marti National Liberation Front. The action was intended to counter Duarte's decision to move the entire legislative assembly for one day Monday to the rural town of Sensuntepeque to hear his speech marking his third anniversary as president.

Duarte's 80-vehicle convoy traveled to the countryside Monday without coming under rebel attack. But in San Salvador guerrillas burned at least 10 buses in three days and set off countless small bombs, bringing back the black smoke of incendiary bombs and the rattle of explosions to city streets for the first time in two years. Public transportation was paralyzed in the city for most of the three days.

Living conditions are falling apart. The electricity was off all day every day this week, as rebel attacks on the power grid worsened a hydroelectric shortage due to a prolonged drought. Phones were intermittent; many homes were without water.

Darkened streetlights led to knots of traffic and ugly confrontations among drivers. Panic buying was seen in some supermarkets.

In contrast to 1980, however, many Salvadorans said the protests and guerrilla attacks were not drawing much support for leftist causes. The police adhered to orders to remain neutral with the protesters no matter what.

The evening television news showed protesters, armed with clubs with nails sticking out of them, shrieking insults into the faces of riot police, who stood expressionless. One bold group of demonstrators spray-painted a leftist slogan on the side of a National Guard troop truck, while the soldiers on top watched in silence.

But the armed forces chief of staff, Gen. Adolfo Blandon, warned Monday that "everything has a limit."

In other developments, a guerrilla peace proposal was released late last month with 18 steps to "humanize" the war in the countryside. Among other points, the guerrilla organization offered to stop using land mines and executing Army informers if the government would stop aerial bombing.

Within hours Duarte rejected the proposal, which also called for negotiations to give a share of power to the guerrillas. The government has always rejected such demands, saying it would not negotiate at gunpoint and that the guerrillas must participate normally in the political process. But a range of Salvadoran editorial writers and foreign diplomats noted that the guerrilla proposals would have brought relief to civilians who have suffered for years in the war.

Duarte came back early this week by proposing 56 new laws to the National Assembly, including a new conscription law, some concessions to the private sector and an extension of the agrarian reform. Duarte also blasted the United States for pressuring him to devalue the Salvadoran currency, the colon, as a means of curbing runaway inflation expected to go above 100 percent this year.

But Duarte failed to generate the public enthusiasm he hoped would help him regain political momentum in time for March 1988 national elections.