Treasury Secretary Donald T. Regan yesterday rejected U.S. intervention in the foreign exchange markets as a way of stopping the depreciation of the yen against the dollar, a process that American business executives claim is costing them heavily in competition in world markets.

Regan rejected intervention following a White House meeting of top administration officials with a number of leading corporate executives who said that the collapse of the Japanese currency is wiping out any benefits they derive from more favorable productivity gains in their factories here.

The fluctuation in the yen, mostly downward, "has been going on for 10 or 20 years," Regan said in a tone of exasperation, "and they the executives want to know: 'What's the answer?' "

The yen closed in Tokyo yesterday at 275.75 to the dollar, near recent record low levels. Regan estimated that the yen has dropped some 70 percent compared to the dollar in the past three to four years. The decline just in 1982 to date has been about 25 percent.

In a wide-ranging press conference, Regan also conceded that economic problems "cut both ways" in terms of election-year impact, but added that, "Even if the economy is not strong, it seems to be in a plus column and growing." He refused to speculate on the October unemployment rate, which will not be announced until the Friday after the national election Nov. 2.

He also:

Conceded that the fiscal 1983 budget deficit "could be larger than $115 billion." He said it depended on the flow of appropriations bills and "the state of the economy over the next several quarters."

Denied that the Federal Reserve Board had changed "its basic policy" away from concentration on money growth targets. The Fed "still thinks of inflation as the number one enemy, and wants to continue in that mode.".

Guessed that the 1983 real economic growth rate would be "around 3.5 percent, give or take a couple of tenths either side."

The White House meeting on the yen yesterday was called by U.S. Trade Ambassador Bill Brock in response to growing concern among manufacturers that the strong U.S. dollar -- especially as compared to the yen -- would continue to cost them dearly in export sales.

Regan said that all of the executives agreed that intervention to stabilize the yen was not the right solution to the problem, and that a study is needed of "what will change the fundamentals." He was quick to say in response to a question that "talking the dollar down was the last thing I would see."

This was an oblique reference to a controversy that surrounded former Treasury secretary W. Michael Blumenthal, who during a period of dollar strength early in the Carter administration was charged with "talking the dollar down." Blumenthal, now chief executive officer of Burroughs Co., was among the business executives present at yesterday's White House meeting.

Regan also took pains to absolve the Japanese government of any suggestion that the yen was being kept artificially low to give Japanese exporters an advantage here or in third markets. "There's no evidence of any rigging the market," Regan said. "It's impossible to rig that yen market because it's so large."

He also said he had no knowledge of a report that the Japanese government itself was trying to put together a package to bolster the yen, noting that the Treasury had not been asked to participate -- as would have been likely -- in any such plan.

Regan said that there will be further government-industry meetings on the foreign exchange problem. "This is something we have to come to grips with because there are many protectionist measures being suggested," he said. "And if we want to avoid them, we have to see what else can be done about it."

In addition to Regan and Brock, the session was attended by Secretary of State George Shultz, Commerce Secretary Malcolm Baldrige, White House aide Edwin Meese, Economic Council Chairman Martin Feldstein, and White House assistant Edwin Harper.

In addition to Blumenthal, business leaders included L.L. Harper of Caterpillar Tractor, Philip Caldwell of Ford Motor Co., Paul Lyet of Sperry Rand, Willard C. Butcher of Chase Manhattan Bank, R.F. Mettler of TRW Inc. and David M. Roderick of U.S. Steel Corp