The United States Information Agency (USIA), invoking bitterly contested regulations, has labeled an American film critical of U.S. policy in Nicaragua "propaganda." An importer thus would have to pay taxes to its government, and because the taxes can be very high in some countries, the labeling would severely cut sales of the film abroad.

A lawyer for film-makers challenging the rules said yesterday this was the first time that the U.S. government has placed such a classification on a film by an independent U.S. producer.

"It's got to be that the USIA can't give up its role of only advancing the administration's positive views of what is going on," said David Cole, a lawyer for the New York-based Center for Constitutional Rights. "It just shows that the definition of what propaganda is is in the eye of the beholder."

The film-makers had claimed in court that the new rules and ones previously in effect gave the USIA broad and unconstitutional censorship powers over films made by the $1 billion documentary film industry. A federal judge agreed with the film-makers in late 1986, but the agency responded this winter with new rules that allow the USIA to label films seeking duty-free status as propaganda.

Film-makers have contended that international sales of their films are crucial to their success and that without USIA's duty-free certification, chances for international sales of the films are severely limited.

The new regulations sparked renewed challenges in a Los Angeles court over what the film-makers allege is the Reagan administration's bid to stifle its critics.

Jane Taylor, a USIA spokeswoman, disputed Cole's claims that the administration has forced the agency to reject the films. "That has never been true and is not true today," she said. "Politics have never been a part" of the review process, she said.

The latest rulings, which apply the new reviewing standards to the six disputed films in the lawsuit, seem certain to renew claims that the government is using the USIA rules to squelch dissent. Most of the films were critical of U.S. policies, and only one won a certificate from the USIA that it was "educational" and recommended for duty-free export under a 1948 treaty.

USIA declared "From the Ashes . . . Nicaragua Today," a 59-minute film about the Central American country, "propaganda." The film, produced in 1981 by the International Women's Film Project of Kensington, is sharply critical of U.S. policies toward the Sandinista government.

A panel of three career Foreign Service officers found the film "is so selective and biased as to constitute propaganda. The film is substantially adapted to indoctrinate, convert and influence the viewer to adopt a favorable view of the political and economic system implemented by the Sandinista government in Nicaragua."

The four other films denied certifications also contained themes critical of U.S. policies on issues ranging from uranium mining to use of herbicides in the Vietnam war. In each case the review panel disputed some of the film's points, questioning, for example, whether the government had done enough to regulate uranium mining.

The rulings were made public Friday night after a USIA lawyer learned that a federal appeals court in California had not issued an order delaying the actions. U.S. District Court Judge A. Wallace Tashima, who in 1986 ruled the agency had no power to act as a censor, had accused the agency of "foot-dragging" in September and ordered it to rule on the films by Friday.

In his earlier ruling, Tashima sided with the film-makers, saying that the USIA has no right to decide which films are accurate and which are inaccurate. That amounted to an effort by the government to interfere with the rights of free speech of the film-makers, Tashima ruled.

The agency has claimed that its rules follow the language of a U.N.-sponsored treaty aimed at improving the flow of educational, cultural and scientific materials among nations. The agency has said it "has no choice" under the treaty but to screen out films that are considered propaganda and fail to meet treaty requirements. Entertainment and films promoting products are specifically excluded from securing the duty-free status under the treaty.

According to government officials, 72 nations are party to the treaty but only the United States and Canada have regulations governing what qualifies for duty-free status under the agreement.