THE TENSION building in Czechoslovakia is in a familiar Soviet-bloc pattern. On one side are a few courageous individuals seeking to make their government obey its own laws and vows. In this case, some 300 intellectuals recently issued a manifesto, "Charter '77," asking that Prague honor the human rights commitments it made in the 1975 Helsinki Declaration. On the other side is a state apparatus fearful that any spontaneous challenge, even a feeble and legal one, will undermine its prestige if not its rule. So the Husak leadership has jailed four activists and taken some of the other grim measures that totalitarian regimes take when they're scared.

But there is a special cast to the Prague winter. The resources available to the activists are different, and possibly greater, than they were at the time of the Prague spring in 1968. These resources may not lie within the country, whose citizens - even the dissenters - remain burdened with the memory of their national tragedy. Many of the Soviet troops and tanks that invaded Czechoslvakia in 1968, after all, are still there.

Legally, the chief new resource is the Helsinki Declaration. Americans have had their own narrow debate about the value of that pledge by 35 nations to strive for a freer flow of ideas and people. Behind the Iron Curtain, however, it has been greeted by individual men and women as a lever with which to pry their own governments toward fulfillment of the governments' solemn and fresh commitment to human rights. Thus, in East Germany perhaps 100,000 people have applied to emigrate to West Germany under the Helsinki accords; Jews and others in the Soviet Union have cited it similarly. In Czechoslovakia, "the Helsinki principles" are being invoked by the human rights movement as its first line of defense.

Politically, the new resource lies in the vigor of West European Communists. Determined to show their electorates that they believe in humanistic values and that they are not Soviet puppets, these parties have sharpened their concern for the treatment of people living under Soviet-bloc rule. Thus has Czech playwright Pavel Kahout appealed to Western Communists (and Socialists) to "help prevent a new witchhunt that would prejudice not only the future of socialism but also of detente." The parties are under heavy domestic pressure to respond.

President Carter, in his campaign, made a hard rhetorical commitment to sustain the craving for liberty and national independence in East Europe. He will be under the same requirement that constrained earlier administrations to do so in a way that does not encourage developments that could backfire either on East Europeans or on East-West relations generally. But certainly that craving is there.