France will continue its campaign of "persuasion and conviction" to get landing rights in New York for the Concorde supersonic jetliner during the new delay in the case ordered by the New York Port authority, President Valery Giscard d'Estaing promised today.

In contrast to angry and gloomy editorials in the French press and open threats of retaliation from politicians and trade unions, Giscard welcomed the delay as a positive sign.

"If the decision was going to be negative, it would have been taken" on Thursday as originally scheduled, asserted Giscard, who telephoned President Carter last Friday to give what the government described as "a firm and solemn warning" about French reaction to a negative decision on Concorde.

Giscard's foreign minister, Louis de Guiringaud, issued a fresh warning that a decision to ban the Anglo-French Concorde would affect French-American trade relations and called the case "the first serious test of French-American relations" under the Carter administration.

The delay is a potentially negative decision was clearly politically welcome for both the French and British governments. Prime Minister Callaghan is flying to the United States in the 1,300-mile-an-hour aircraft Wednesday and would have been at the White House when the decision was to be announced.

French voters go to the polls on Sunday in the first round of bitterly fought nationwide municipal elections. A negative decision on Concorde would have been a major handicap for Giscard's party, which has been accused in the past of being too soft on Concorde and or becoming too friendly with Washington in general.

French Communist leader Georges Marchais attempted to turn the delay itself into a political issue by saying that it had been arranged by Carter "to aid the Giscardians." Gaullist, Socialist and independent leaders all produced statements warning of direct consequences if Concorde were rejected, and Former Foreign Minister Michel Jobert said France should cancel its political membership in the Atlantic alliance if the decision is negative.

Citizen groups presented U.S. Ambassador Kenneth Rush with what they said were petitions with 113,568 signatures from Concorde supporters. Saying that he was touched by the gesture, Rush added that "there is even at the highest levels in France a certain misunderstanding about the ability of the federal government to influence" the port authority's decision.

While French and British officials denied that their governments had requested the delay, Gilbert Perol, general manager of Air France, did concede that the state-owned airlines had asked the New York authority to consider new technical information on noise control. This request was the basis for the authority's surprise decision yesterday to put the case off to a later unspecified date.

"We will use all methods of persuasion and conviction during this delay>" President Giscard told a radio interviewer, and he predicted that Britain and France would prove that "Concorde can easily pass a comparison with the planes currently used in New York."

This had happened in Washington, he said, "where the anti-noise campaing has completely stopped."

Concorde has been landing at Washington's Dulles Airport since May on a 16-month trial basis authorized by the Department of Transportation. Concorde's manufacturers> who have put more than $3 billion in British and French taxpayers' money into developing the nine Concordes currently in use, maintain that New York landing rights will make the needle nose jet, which crosses the Atlantic in four hours, commercially competitive.

The unions and politicians here have rallied arround the concorde both because of the 100,000 jobs they say are at stake and as a matter of national pride.

The French aviation industry is also floating suggestions that a negative decision on Concorde will kill chances for American-French cooperation on subsonic aircraft and push France into new ventures with West German and British manufacturers for a European aviation industry.