The dollar was firm in world foreign exchange trading yesterday after Wednesday's hectic response to the Iranian crisis. Gold prices fell.

The British pound leaped nearly 4 cents against the dollar in London after the Bank of England announced an increase of three percentage points, to a record 17 percent, in its minimum lending rate to financial institutions as an anti-inflation tactic.

The move, which makes the British currency more attractive to foreign buyers, sent the pound to $2.1455 at the close, up from $2.1095 Wednesday. The pound has gained almost 6 cents in a week.

In late New York trading a pound cost $2.1503, up sharply from $2.1165 Wednesday.

In Tokyo, the dollar opened sharply lower but gained for most of the day. It wound up at 245.525 yen, lower than Wednesday's 245.975 yen.

Late dollar rates in major European trading centers, compared with Wednesday's late rates were: Frankfurt, 1.7822 West German marks, down from 1.7823; Zurich, 1.6540 Swiss francs, up from 1.6525; Paris, 4.1790 French francs, down from 4.1838; Amsterdam, 1.9825 Dutch guilders, down from 1.9838, and Milan, 828.95 Italian lire, up from 827.90.