Former prime minister Jacques Chirac brusquely rejected pressure from President Valery Giscard d'Estaing to drop out of the race for mayor of Paris today and appeared to be pushing toward a total and open break with his old political ally.

Chirac has refused to meet with his successor, Prime Minister Raymond Barre, who was told by Giscard yesterday to find a compromise solution to the "disorder" that the mayor's race has spread through the coalition that governs France.

Instead, Chirac sent Barre a letter asserting that he would withdraw only for "extremely serious and compelling reasons." In a radio interview here tonight, he reiterated his determination to see the campaign through "so that Paris will not fall into the hands of the Socialist-Communist" bloc.

"Giscard offered a compromise, but Chirac wants nothing less than a surrender," said a political analyst with ties to both camps.

Chirac heads the Gaullist party, the largest group in Parliament. He helped Giscard, founder of the small Independent Republican Party, to a narrow victory in the 1974 presidential election but quit as his prime minister in August.

Campaigning for the March election of the first mayor of Paris in 100 years intensified today as it became clear that Barre's conciliation mission was collapsing.

Giscard's candidate, Industry Minister Michel D'Ornano, signaled that he would try to make the Gaullist record of managing Paris for two decades the main issue of the campaign by traveling to a multimillion-dollar complex of slaughterhouses just outside Paris that has never been used because of poor planning and design.

His visit recalled the charges of payoffs for the Gaullists on this and other urban projects that are usually made by the leftist opposition.

In his toughly worded statement yesterday, Giscard also stressed his administration's record in "stopping the burying of Paris under concrete and skyscrapers" that the Gaullists had permitted.

Barre formally announced tonight that D'Ornano is ready to drop out of the race if a compromise candidate could be agreed on by the coalition, which includes the Gaullists. After noting Chirac's refusal, Barre said that he "deplored the prolonging of a worrisome situation" for the coalition, and implied that Chirac's candidacy is undermining efforts by Barre and Giscard to revive the flagging French economy.

Both sides are also resorting to publicizing public-opinion polls to support their campaigns for 109 scats on the city council, which elects the mayor from its ranks.