Del. Walter E. Fauntroy (D-D.C.), until recently a champion of increased foreign aid to Haiti, called yesterday for international military intervention there after more than two dozen Haitians were killed during a national election Sunday that subsequently was called off by the provisional government.

"I'm just appalled and outraged that citizens standing in line to vote should be gunned down and savagely hacked to death," said Fauntroy, chairman of the congressional task force on Haiti and a leading congressional authority on Haiti since the mid 1970s. "I think the situation now requires an international response."

Fauntroy, who opposed a similar proposal for intervention three months ago, said he conferred with State Department officials yesterday about his plan for deploying an international peace-keeping force to guarantee Haitians a free election. He charged that the provisional government headed by Lt. Gen. Henri Namphy cooperated with remnants of the paramilitary force of the deposed dictatorship of Jean-Claude Duvalier in permitting Sunday's reign of terror.

"I resisted this before, but now that they engaged in this brutal action, the only hope for the people is international intervention," he said.

Elliott Abrams, the assistant secretary for inter-American affairs, said last night that military intervention is "not one {alternative} I think we should turn to because where does that lead us?"

"It's not inconceivable there's a larger role for {international} observers to play," he said on the MacNeil/Lehrer Newshour last night. "But security must be provided by the {Haitian} government."

The Reagan administration announced Sunday that it had cut off about $1.2 million in nonlethal military aid and roughly $44 million in economic assistance to Haiti, after the cancellation of the election and the violence in which armed gangs shot or hacked to death 27 persons.

Stephen A. Horblitt, Fauntroy's legislative counsel who was among about 200 international observers of Haiti's election, rode in a car that was repeatedly fired upon by a military policeman with rifles, he said. None of the five passengers was injured.

"We hit the floor of the car," Horblitt recalled yesterday. "The only thing that saved us is that our driver knew what he was doing and turned in the right direction, away from the fire . . . . We saw bodies on the street downtown as we sped to the Holiday Inn.

"This is an all-out war against the Haitian people by thugs and an all-out war against the U.S. and other countries that favor free elections."

Horblitt, Nancy Soderberg, an aide to Sen. Edward M. Kennedy (D-Mass.), and Alfred Cumming, an aide to Sen. Bob Graham (D-Fla.), were among a 30-member observation delegation sponsored by the National Democratic Institute for International Affairs. The White House also sent a team of 15 observers, headed by Roger Moore, the general counsel of the Republican National Committee.

Fauntroy was denied entry to Haiti over the weekend because of a letter that he and 43 other members of Congress sent to Namphy Oct. 14, protesting his government's failure to control mounting violence and human rights violations surrounding the election.

"In particular, we are alarmed at the direct involvement of the Haitian security forces in a series of attacks on unarmed civilians and in raids on poor neighborhoods, which have resulted in scores of deaths and injuries and untold damage to property," the letter stated.

Fauntroy's call for military intervention marks a dramatic departure from his long-held view that social and economic reforms in Haiti could be brought about with carefully targeted and controlled U.S. aid.

In 1986, after the downfall of Duvalier, Fauntroy helped create the bipartisan congressional task force on Haiti, which began prodding the provisional government to make reforms and hold an election.

As chairman of an international development institutions and finance subcommittee of the House Banking Committee, Fauntroy played a key role in more than doubling U.S. economic aid to Haiti to more than $100 million last fiscal year.

Despite the aid, Horblitt said, it became clear in the last seven months that remnants of the Ton-Tons Macoute, the disbanded Duvalier paramilitary force, had become more active and the government had done nothing to prosecute corrupt officials.

When historian Arthur Schlesinger Jr. suggested this fall that a multilateral peace-keeping force be sent to Haiti to guarantee a free election, Fauntroy strenuously argued against the plan.

"Like the administration, I believed what Gen. Namphy and the National Government Council told us," Fauntroy said. "Namely, that they would do all they could to assure the elections came off. I now believe we were misled."