President Reagan and Federal Reserve Chairman Paul Volcker met privately Monday to discuss their economic policy differences, sources said yesterday.

Murray Weidenbaum, chairman of the President's Council of Economic Advisers, acknowledged yesterday that the Volcker meeting had been scheduled for Monday afternoon, although he said he had not attended the meeting and could not confirm that it took place. "I understand the chairman requested a personal meeting," Weidenbaum said.

The White House and the Federal Reserve both declined official comment on the meeting. Several administration officials yesterday expressed suprise that the meeting already had taken place. They said they had expected it later this week.

"Go ask the White House" responded Fed spokesman Joe Coyne to all questions on the subject.

White House Communications Director David Gergen told reporters "I'm not at liberty to go into when the president will meet with" Volcker. However, press spokesman Larry Speakes, whose office had earlier denied there had been a meeting, said later yesterday "we're officially no-commenting it . . . but I think it's generally known."

The sudden lowering of a veil of silence around the subject of Reagan's relations with the Fed comes after the president and a number of senior administration officials have stepped up public criticism of the Federal Reserve in recent weeks. As interest rates have climbed, despite the deep recession, Reagan and his aides have blamed the Federal Reserve for unsettling financial markets by allowing erratic money growth.

Last Friday the president complained "I think we need to have more cooperation from the Federal Reserve Board with regard to the money supply and a more consistent pattern" in order to bring interest rates down.

Volcker, who in previous meetings with the president has apparently lectured him on the need for a more restrained fiscal policy, last week told Congress that prospective budget deficits were too large. It is these large deficits that are frightening markets, thus raising interest rates, and which threaten to usurp too much of the available credit in the economy, Volcker warned. He was expected to carry that message to the president again this week.

Despite the complaints over monetary policy, Volcker has stressed that the administration is in basic agreement with the Fed on the broad thrust of policy. White House criticism has centered on short-term fluctuations in money growth above and below the Fed's targets, rather than on the targets themselves. The Fed Chairman said last week that these fluctuations were unavoidable and did not matter as much as administration officials claim.

There has been a surge in money growth so far this year, which has pushed the money supply well above its target range. This has been accompanied by higher short-term interest rates, Weidenbaum said yesterday. Although more money generally would lead to lower, rather than higher, interest rates, officials suggest that rates have risen with the money supply because of financial market fears that the excessive money growth will lead to more inflation.

However, many economists believe that the tight money and large projected budget deficits are keeping interest rates high.