The start of the highly touted European Monetary System appeared to suffer at least a temporary delay yesterday when France insisted on certain changes in the Common Market's farm pricing system as a pre-condition.

To bring "a zone of menetary stability" to Europe, eitht participating Common Market countries had agreed to link their currencies together in a common band similar to the existing European "snake."

Central currency rates for the eight EEC members -- only Great Britiain had opted out -- were to be quoted against a new European Currency Unit (ECU) begining January 2.

A second stage, if the first succeeds, would provide a much closer monetary policy, and backed by a massive support fund contributed by each participating country.

U.S. officials, who have been maintaining an arms-length, but polite attitude about the EMS, had no comment yesterday. But privately, they believe that French President Valery Giscard d'Estaing has such a strong political commitment to the EMS that present difficulties eventually wll be irouned out.

In a statement issued by French Prime Minister Raymond Barre, the government of France insisted that before new currency relationships are tightened, the EEC countries must first agree to phase out farm subsidies, now used to offset the effect of currency fluctuations.

The subsidies tend to benefit German farmers whose products otherwise would not be competitive because of the high-priced German mark. They also give a break to weak-currency food importing countries like Great Britain. And the way the complicated system of compensatory payments works, farmers in countries like France and Italy get lower net prices for the same food products because they must pay export taxes.

In Bonn, a spokesman for the West German government -- equally committed as France to the institution of the Ems/ -- said "every effort" would be made to clarify the situation, but acknowledged that the French had thrown a roadblock aginst the January 2 start-up date.

The first stage of the EMS would have allowed a maximum fluctuation among the currencies of only 2.25 per cent, except for the Italian lira, which for a temporary period would be allowed a 6 per cent fluctuation. Great Britain had decided thqt to bring its currency so closely in line with the others would cause too much belttightening.

U.S. officials have tended to be skeptical of the EMS, a bit unsure whether its operations would tend to help or weaken the dollar. They see in it a German and France hankering for "the good old days" of fixed rates, which U.S. officials don't think can work in a (European) world of disparate inflation rates and social attitueds, especially toward unemployment.