AT FIRST GLANCE, the travel agents' protest

demonstration in Paris had its comic aspect. But look again. What do you suppose the reaction in this country would be if the government suddenly decreed that you could spend no more than $270 abroad in the coming year?

The French government, having just devalued the franc for the third time since it came to power two years ago, is desperately trying to conserve foreign exchange and stave off a fourth devaluation. Shutting off tourism for a year seems to President Mitterrand less undesirable than shutting off, for example, imports of foreign-made consumer goods. The Common Market is now under severe internal strain. Explicit and sharpened protectionism, of a sort that might have put the Common Market in real jeopardy, was one of the possibilities under discussion in France in recent weeks. There was a good deal of support for it within Mr. Mitterrand's own Socialist Party. But he stoutly rejected the idea and, if the resort to travel restrictions seems extreme, it is surely a great deal less dangerous than any alternative.

France has now embarked on a genuinely rigorous austerity program, of which the travel rules are the most visible but not necessarily the most important element. There are also mandatory loans to the government, higher taxes and higher utility rates. Having failed in its attempt to kick the French economy into high growth with high spending, the Mitterrand government is struggling to get its domestic and foreign deficits under control.

The people and parties now in power in the Common Market countries remain firmly committed to it, but the opposition is not trivial. In Britain, the Labor Party published its new platform repeating its pledge to take the country out of the Common Market if the party should win the election that will be held sometime within the next year.

For Americans, the point is that the great worldwide deflation is generating high tension as people everywhere are forced back a step away from the abundance that once seemed to lie just ahead of them. The most dramatic examples are in Latin America, but the same effects are clearly visible in the wealthy industrial countries of Western Europe. The United States continues to be the dominant force in the world's trade, and every turn in American policy has consequences abroad--often much sharper there than here. Americans now need to exercise great care that their own decisions do not aggravate the troubles of other countries whose economies are now closely integrated with their own.