The Carter administration said yesterday it has received some early indications that Japan finally may be about to lower some of its longstanding barriers to American exports on a few specific commodities.

Robert S. Strauss, the President's Special Trade Representative, said in an interview that officials had been given "some positive signs" that the Japanese soon may accept American shipments of citrus fruit and meat.

He also predicted that Tokyo would ease existing tariffs on American-made calculators and film, even though Japan is actively involved in production of both items.

At the same time, Strauss said the Japanese have agreed in principle to join the U.S. in pressing actively for a sharp reduction in tariffs in the upcoming sessions of the multilateral trade negotiations in Geneva.

Although he declined to discuss any specifics Strauss said the Fukuda government had agreed to be "reasonably supportive" in developing a formal plan for traiff-cutting.

That step is the first the trading nations have scheduled for bargaining in their bid to hammer out a worldwide trade agreement by the early part of next year.

Strauss's remarks obviously were intended to dispute reports this past weekend that the two nations had failed to make progress in discussions between negotiators from both sides.

Alan W. Wolff, Strauss's chief deputy, was quoted in wire service reports as saying he was "disappointed" by the failure of the negotiators to move ahead. Other officials gave a similar impression.

However, administration sources speculated yesterday that Wolff had appeared pessimistic in part to avert setting off a controversy in politically-sensitive Japan, where trade liberalization is a volatile issue.

Strauss insisted yesterday that, contrary to those initial reports, he and other officials here were "extremely encouraged" by the Japanese willingness to support tariff reductions, and hopeful about the trade talks.

On the prospect of possible reductions in barriers to U.S. products such as citrus and meat. Strauss said he still had "no promises" of trade liberalization from the Japanese, but saw early signs of improvement.

Permission to export American citrus products and meats to Japan would be a significant step in the eyes of trade negotiators. Barriers involving both commodities have been a sorepoint between the two sides.