The French Communist Party this weekend stepped up its efforts to appeal to racist sentiments here in an apparent search for votes for party leader Georges Marchais in this spring's presidential elections.

Saturday afternoon, Communist Mayor Robert Hure of the distant Paris suburb of Montigny-les-Cormeilles led a demonstration at a housing project under the windows of a Moroccan family accused in local party leaflets of being drug traffickers.

The local police chief said he knew of no basis for the accusation, and the family's real crime seems to be that it is Arab.

At almost the same moment, Marchais was telling an audience of several thousand in Saint Denis, the bedroom suburb that symbolizes communist control of the working-class "Red Belt" around the capital. "We don't want new Harlems or new Sowetos in the Paris suburbs. We don't want new Chicagos either." For the French, Chicago is still synonymous with gangland lawlessness.

Marchais' words consecrated the linkage of the party's already clear appeal to "law and order" themes with the thinly veiled attacks on immigrant workers, mostly black and Arab.

"Marchais," said one of the growing number of dissident communist intellectuals, "is appealing to the the same kind of blue-collar racism you have in America, but which the French Communists used to fight against. His real constituency is the same as George Wallace's."

The weekend incident fits into a emerging pattern of actions and statements with clear racial overtones by communist-controlled municipalities all over the country. The first instance to receive publicity came on Christmas Eve when a domitory housing 318 black African workers from Mali was sacked and bulldozed by communist strong-arm squads in the suburb of Vitry.

Even inside the Communist Party, it was widely thought that the mayor of Vitry, who has a reputation of not always understanding the intricate subtleties of the party line, would be disavowed for making a major mistake. The first commentaries of the Communist Party organ L'Humanite pointed in that direction.

A week later the head of the Paris Mosque, Rector Si Hamza Boubakeur, publicly called on Marchais to denounce the action speedily "to avoid a serious breach between the Communist Party and the Moslem proletariat in France and the rest of the world." The party leader eventually replied in an open letter filling more than half a page of L'Humanite' saying that he "approves without reservation" the action of "my friend Mayor Paul Mercieca of Vitry."

In Ivry, a communist town councilman sent covering letters with applications for the municipality's summer camps saying that there would be a 15 percent quota for children of foreigners since the town authorities wanted to fight the government's policy of turning the communist suburbs into "ghettos."

Marchais tries to downplay the racial aspect of his policy by criticizing the government's immigration policies ina period of economic downtown. He accuses the government of hyprocritically encouraging illegal immigrant workers while officially encouraging the legal ones to go home.

In the case of Vitry, Marchais accused the mayor of a neighboring town who had closed for repairs his municipality's dormitory for Malians, of trying to foist his race problems on a communist-run city.

As Marchais spoke Saturday, Malians were demonstrating outside the party's national headquarters "against the racist, antiworker policy of the French Communist Party."

The indications are that the Marchais strategy is a desperation measure to stave off what could be the party's poorest electoral showing since World War II. Large numbers of the educated longtime communist voters dedicated to the leftist unity pact that their party sabotaged are obviously preparing to punish their own leaders by voting for Socialist Party candidate Francois Mitterrand on the first round of the elections without waiting for the runoff between the two top contenders.

The Communist Party has been trying to compensate for the massive losses it expects among people such as school teachers by signing up unaffiliated voters in party-controlled towns. It is estimated that 6 to 9 percent of the population is not registered in any party. A party registration drive in which Communist municipal employes canvassed door-to-door to register such people as Communists wound up with the courts annulling the registrations of all persons who had been signed up in their own homes.

The Marchais policy is also likely to cost the party its considerable vote in France's large black-populated Caribbean islands of Martinique and Guadeloupe, whose natives are French citizens and vote in national elections. The Martinique Communist Party already had called for abstention in the coming election. The Guadeloupian party is widely expected to do the same.

The attitude of the French Antillean parties, which are considered particularly close to Moscow, is seen by close students as a sign that the Soviets may be prepared to dump Marchais after the presidential elections.

Even though Marchais has drawn close to the Kremlin in recent years, he was estranged from them for an extended period when he followed a Eurocommunist line stressing independence from Moscow.

At the height of his Eurocommunist phase, Marchais traveled to Algeria, Mexico, Yugoslavia and Romania apparently seeking alternatives to Soviet financing of his party.

Algeria is understood to have been particularly helpful, channeling funds through the party-controlled engineering and building companies that specialize in construction work in communist-run municipalities. But under Algerian President Chadli Benjedid, who take a distinctly more moderate line than his predecessor, that source of funds is said to have dried up. As a result, say some analyst, marchais no longer has any reason to restrain the natural bent of the mass of his electorate to make North African Arabs feel unwelcome in France.