The dollar retreated yesterday against most currencies in lackuster foreign exchange trading, but firmed against the British pound and Swiss franc in New York. Gold prices fell.

Gold finished the day at $392 a troy ounce in both London and Zurich, down $3 from the Wednesday close of $395 in both centers.

In new York, the late price of gold fell $9 to $388 an ounce. On the Commodity Exchange, the price of gold futures for October delivery fell $7.30 to 388.60 an ounce.

In Tokyo, the dollar slid to 233.775 yen from 234.80 yen Wednesday. The dollar also had a poor day in London. The British pound recovered some to finish at $2.1135 against Wednesday's $2.1102, its lowest late rate this month. But in New York, the dollar gained against the pound. The late rate for the pound was $2.1125, compared with $2.1165 Wednesday.

Late dollar rates in Europe, compared with Wednesday's late rates, were: Frankfurt, 1.8015 West German marks, down from 1.8045; Zurich, 1.6567 Swiss francs, down from 1.6580; Paris, 4.2240 French francs, down from 4.2250; Amsterdam, 2.0015 Dutch guilders, unchanged, and Milan, 829.45 Italian lire, down from 829.85.