PORT-AU-PRINCE, Haiti (AP) _ Business and labor organizations on Friday called for a one-day work stoppage to protest an attack on the governing Council of State that killed a union leader and wounded two politicians.

The country was quiet Friday, but the assault cast doubt on the fragile civilian government's plan to hold presidential elections in September.

The independent Electoral Council postponed a press conference called for Friday to present its draft electoral law. Council member Emmanuel Ambroise said the meeting was called off indefinitely ''in consideration of the situation.''

On Thursday, four gunmen - two wearing army uniforms and two in civilian clothes - burst into the courtyard of the Hotel Santos, where the Council of State was to meet with political, labor and business leaders to discuss a wave of violent crimes. At least 13 people have been killed in the capital, Port- au-Prince, in random crimes since Tuesday.

The assailants opened fire on a group of people with M-16 automatic rifles, killing union activist Jean-Marie Montes. Council member Serge Villard and Emmanuel Mani, a member of the Socialist National Progressive Party, were wounded and taken to a hospital, where they were reported Friday to be in ''stationary condition and out of danger.''

The Chamber of Commerce and Industry declared that Saturday would be a day of mourning and urged people to stay home from work. The proposal gained the support of the Autonomous Union of Haitian Workers and the Radical Labor Union.

The 19-member civilian council, which governs alongside President Ertha Pascal-Trouillot, said it would resume its meeting Saturday with the leaders of the 11 institutions it represents to discuss the climate of insecurity in the country.

The Army High Command condemned the attack and promised to track down the assailants and bring them to justice.

Immediately after the attack, the Congress of Democratic Movements, a socialist political alliance, branded the assault ''an attempt to destabilize and compromise whatever is on the road to elections.''

The U.S. Embassy called it an act of barbarism ''against the entire democratic process and against the aspirations of the Haitian people for secure and free elections.''

Haiti's last independently run elections were aborted on Nov. 29, 1987, when army-backed thugs shot and hacked to death at least 34 voters at polling stations.

The apparent involvement of soldiers in Thursday's attack cast further doubt on the army's intentions as Haiti moves toward establishing what would be its first democratically elected government since independence from France in 1804.

The Army High Command has pledged to support Mrs. Pascal-Trouillot. She was appointed president in March to replace military ruler Lt. Gen. Prosper Avril, who fled into exile after a weeklong popular uprising.

But skeptics have questioned the willingness of the notoriously ill- disciplined and corrupt army to relinquish privileges gained over many years.

Mrs. Pascal-Trouillot did not comment on the attack. Her last public statement was on Monday, when she said illness had forced her to cancel a scheduled meeting with U.N. Secretary-General Javier Perez de Cuellar in New York.

Mrs. Pascal-Trouillot and the Council of State, which has veto power over her decisions, have been at odds over her appointment of Marie Violene Legangneur as finance minister.

Council members consider Ms. Legangneur to be a sympathizer of the 29-year dictatorship of Jean-Claude ''Baby Doc'' Duvalier, who fled into exile in 1986, and his late father, Francois ''Papa Doc.''

The council has said it will not approve any electoral law signed by the finance minister. The law is necessary to hold general elections.