Paris — While West Germany and other NATO allies are profoundly uneasy with the deployment of American Pershing II missiles in Europe, France is standing firm in its support of such deployment if the Geneva negotiations break down.
The French reject the recent Soviet arms control offers as, in the words of one Defense Ministry official here, ''merely a propaganda offensive of major proportions.''
The great fear in Paris is that the Soviets will succeed in convincing West Germany not to take the missiles. A major worry of the French government, some analysts here say, is that a military disadvantage could force West Germany to go neutralist.
A ''decoupling of the European continent and the American continent,'' President Francois Mitterrand told the Bundestag in Bonn last week, ''would put into question the maintenance of equilibrium and thus the maintenance of peace.''
The firm French position stems from President Mitterrand's belief that the Soviet SS-20 missiles already in place represent a critical danger to Western Europe.
It also reflects a fear that reductions in the Soviet force will be tied to the size of the French nuclear force, which operates independent of NATO, while leading to a fundamental Soviet military advantage over the West.
France is not directly involved in the Pershing deployment. No missiles will be installed on its soil. But the French position is important because it influences the West German Social Democratic Party, potential German voters, and public opinion in general in Europe.
''France's support is crucial,'' one United States diplomat here said. ''President Mitterrand has significant international stature, and as a European and a Socialist, he has more influence in this matter on the Germans, and the Social Democrats in particular, than we ever could.''
Ever since President Mitterrand's election in May 1981, his Socialist government has stood firmly behind the United States on the question of medium-range missile deployment.
Mr. Mitterrand supported President Reagan's ''zero option'' proposal for European nuclear balance and continues to do so, although he has been quoted as saying he would accept a compromise: retention of some Soviet missiles in return for a US agreement to not deploy the Pershings.
Still, the French are skeptical about accepting many Soviet missiles. They are even worried that President Reagan may give away too much to the Soviets at the Geneva strategic arms talks (START).
The Socialist Party's secretary in charge of international affairs, Jacques Huntzinger, said last week that the Soviets would have to reduce their SS-20s to between 10 and 20, not the 50 or so Washington is apparently considering, ''before there is a real reduction in Soviet capacity, before there is anything acceptable or meaningful.''
A ceiling of 50 SS-20 missiles - the number US arms negotiator Paul Nitze reportedly proposed in Geneva last July in return for a US agreement not to deploy its weapons - would fail to block the present Soviet capacity ''to destroy every major strategic target,'' according to Mr. Huntzinger. Though Huntzinger is not a member of the government, the Socialist Party usually mirrors government positions on security matters.
This hard-line French stand is backed by a political consensus in the country. Except for the Communists, every major political group supports Pershing deployment. There is no major peace movement here.
The absence of large numbers of pacifists is a result of two factors, analysts argue: First, France is a Roman Catholic, not a Protestant country. And secondly, France's nuclear force is independent of NATO.
In West Germany and other Protestant northern European countries, pacifism has found its roots in support from churches. Here, in contrast, the Roman Catholic Church has steered clear of the nuclear issue.
''The French church is very hesitant to use theological points to argue temporal issues,'' explained a Defense Ministry official.
Being able to pull their own nuclear trigger is also crucial. ''Because we control our own nuclear weapons, and because they are crucial to our independence, no great opposition to them has been able to develop here,'' said Dominique David, deputy director of the French Institute of Military Studies. ''In contrast, America calls the shots for West Germany, and for the Germans, that's frightening.''
To assure the independence of their nuclear force, the French insist there can be no link between their own nuclear force and American nuclear weapons. The Soviets have demanded this linkage by proposing to reduce their number of medium-range missiles targeted on Western Europe to parity with French and British nuclear forces, currently 162 missiles.
The French argue that their forces are purely defensive, constituting no threat to the Soviets. ''We have 98 missiles, the Soviets 7,320 even before the SS-20,'' explained a Defense Ministry official. ''We can retaliate, but we can't attack the Soviets. It's preposterous to compare the Soviet force to the French force.''
Mr. Mitterrand made this clear to the West Germans in his speech to the Bundestag. ''If one of the two great powers destroyed all its medium-range missiles,'' he said, in a clear reference to the zero option, ''it would still retain thousands of missiles. But (if France did this) it would lose a decisive element of its deterrent capacity and thus the guarantee of its security.''
Any linkage between Soviet and French nuclear forces, the French argue, would also put NATO at a permanent military disadvantage, and effectively separate Europe from America.