NEW YORK, SEPT. 14 -- The dollar rose against most major currencies except the Canadian dollar today as it extended Friday's advance.

Gold prices edged lower. Republic National Bank of New York quoted a bid for gold of $456.50 a troy ounce, down slightly from $457 Friday.

The dollar is "still building on the momentum that we picked up on Friday," said James Vick, vice president and senior corporate trader at Manufacturers Hanover Trust Co.

The Commerce Department reported Friday that a plunge in U.S. exports helped lift the U.S. trade deficit to a record $16.5 billion in July, the fourth consecutive monthly increase.

The news triggered a steep slide in the dollar's value, but the decline was short-lived and the U.S. currency quickly rebounded.

Many investors were impressed by the dollar's resilience and continued to buy the currency today, traders said.

The massive U.S. trade deficit has been at the root of the dollar's recent weakness. Friday's statistics showed that a substantial decline in the value of the dollar has not yet produced a big reduction in the nation's trade shortfall.

Investors initially sold dollars Friday out of concern the Reagan administration could allow the dollar to fall further in an attempt to cut the trade deficit. When the dollar is down, imports are more expensive, but U.S. goods become cheaper overseas.

Traders said the dollar also benefited today from a statement by Treasury Secretary James A. Baker III that foreign-exchange rates have been reasonably stable over the past few months.

In Tokyo, where the global trading day begins, the dollar rose 1.37 Japanese yen to close at 143.90 yen. Later in London, it was quoted at 144.83 yen. In New York, the dollar was quoted at 144.47 yen, up from 143.90 yen late Friday.

In London, the British pound was quoted at $1.6345, cheaper than the $1.6550 in late Friday trading. By the end of New York trading, the pound stood at $1.6375, less expensive than the $1.6430 posted late Friday.

Other late dollar rates in New York, compared with late Friday, included: 1.8165 West German marks, up from 1.8070; 1.5075 Swiss francs, up from 1.4970; 6.0665 French francs, up from 6.0445; 1,310.00 Italian lire, up from 1,309.00, and 1.3170 Canadian dollars, down from 1.3184.

Other late dollar rates in Europe, compared with late Friday, included: 1.8225 West German marks, up from 1.7927; 1.5110 Swiss francs, up from 1.4835; 6.0825 French francs, up from 6.0025; 2.0505 Dutch guilders, up from 2.0395; 1,310.60 Italian lire, up from 1,300.00, and 1.3210 Canadian dollars, up from 1.3177.

The price of gold fell in London. Gold was quoted in late trading at a bid price of $455.75 a troy ounce, down from $458 late Friday.

In Zurich, gold closed at a bid $457.50 an ounce, down from Friday's close of $458.50. Earlier in Hong Kong, gold fell $1.37 to close at a bid $457.86 an ounce.

Gold for current delivery closed at $456.50 a troy ounce at the New York Commodity Exchange, down slightly from $456.80 late Friday.

Silver was quoted in London at a bid price of $7.67 a troy ounce, down from Friday's $7.72.

At the New York Comex, silver for current delivery closed at $7.641 a troy ounce, down from $7.700 late Friday