The U.S. dollar fell on European money markets and in New York yesterday and dealers said the decline was a result of speculation in the West German mark.

Gold's price declined. In Zurich it closed at $224.875 an ounce aginst $225.125 Thursday. In London it was unchanged at Thursday's $224.875.

In Frankfurt the dollar fell to 1.8625 marks, from 1.8715 Thursday. In Zurich it ended the week at 1.5265 Swiss francs, down from 1.5440. In Paris, the dollar fell to 4.2525 francs, down from 4.2575; in Brussels to 31.215 Belgium francs, from 31.355; in Amsterdam to 2.0215 guilders, down from 2.0299. The dollar hit a 31-month low in Milson, at 813.25 line compared with 814.85.

In London the pounce rose to $1.9335 from $1.9899.

In Tokyo, where markets are half a day ahead of U.S. and European markets, the dollar reacted to Thursday's recovery closing at 186.70 yen, up from 186.95. However, it eased in New York to 186 yen.

Other New York closing prices: 29.40 Belgium francs, 4.2575 French francs, 1.8613 German marks, 2.0290 Dutch guilders, 814.50 Italian lire and 1.5275 Swiss francs.