The independent counsel who successfully prosecuted former White House aide Michael K. Deaver said yesterday there is "too much 'loose money' " in Washington and that until attitudes about ethical standards change "there is little that prosecutors can do except put a thumb in the dike."

In a sharply worded statement made on the steps of the U.S. Courthouse, Whitney North Seymour Jr. delivered a scathing assessment of influence-peddling by former government officials and charged that the Watergate-era Ethics in Government Act, which governs the contacts that former government officials may make after they leave the federal payroll, is so riddled with loopholes that it is impossible to enforce.

The "problem is too much 'loose money' and too little concern about ethics in government," Seymour said.

"Vast sums of money are on call to representatives of major corporations, defense contractors and foreign governments to buy influence and favors," Seymour said. "Much of that money is paid to 'consultants' whose stock in trade is their friendship with persons in high office. Washington money men will continue to undermine public confidence in government until lawmakers, business and community leaders and individual citizens decide to cry 'enough.' "

Seymour singled out for criticism Secretary of State George P. Shultz, whose testimony praising Deaver's integrity during the trial of the former White House deputy chief of staff, Seymour said, reflects the Reagan administration's indifference toward ethical issues.

"He {Shultz} stepped forward in his cross-examination, gave a ringing endorsement of the honesty and integrity of a defendant on trial in a criminal case charged with a serious felony and he never even bothered to read what the charges were," Seymour said. "The jury decided that was irresponsible. I don't see how any right-thinking citizen could conclude otherwide."

A State Department spokesman declined to coment on Seymour's statement. A reporter who attempted to ask Shultz about it during a Christmas tree lighting ceremony at the department was hissed by employes.

Deaver was convicted Wednesday on three counts of lying about his lobbying and faces a possible sentence of 15 years in prison and a $22,000 fine. Seymour has said Deaver lied to a congressional subcommittee and a federal grand jury to block investigators from discovering whether the many contacts he made with senior administration officals after he became a well-paid lobbyist violated the law.

Randall J. Turk, one of Deaver's lawyers, said Seymour's comments were "an outrageous and flagrantly inappropriate act by a prosecutor" and suggested that the New York lawyer, who ran for that state's Republican Senate nomination in 1982, was using the conviction to revive his political ambitions.

"Having utterly failed to prove Mr. Deaver violated the Ethics in Government Act, Mr. Seymour, who has had political ambitions for years, now is making speeches about corruption in this administration. . . , " he said.

Turk described the prosecutor's attack on Shultz as an "attempted public intimidation of witnesses who supported Mr. Deaver" and said it was "uncalled for and totally unprofessional."

In his statement, Seymour praised legislation pending in the Senate Judiciary Committee that would revise the ethics act. He called the bill "a major start" toward changing a law that is riddled with holes. "The public has a right to expect that a statute bearing such a noble-sounding name will prohibit unscrupulous conduct. The present statute does not do that."

Sen. Arlen Specter (R-Pa.), one of the bill's cosponsors, said yesterday, "I don't know details about the Deaver case, but I do know the present law is vague, elusive and hard to define."

Specter declined to comment on Seymour's statements about the administration's attitude toward ethical issues, but Sen. Howard M. Metzenbaum (D-Ohio), another cosponsor of the proposed revision, said the prosecutor was "right on the money."

The bill would contain a flat, one-year prohibition on former senior government officials from lobbying their old agencies and would strip the Office of Government Ethics of its power to divide agencies into compartments and thus to allow workers to lobby sections of their former agency.

Under such a ruling, the White House was split into nine agencies in 1983, a decision that Seymour said yesterday made it difficult to prosecute Deaver for alleged violations of the ethics act.

Seymour blamed the Canadian government for Deaver's acquittal on a count that alleged he lied about his efforts to help resolve an acid rain dispute with Canada while at the White House. Allan Gotlieb, the Canadian ambassador to Washington who had hired Deaver as a lobbyist for his country and was one of Seymour's key witnesses, invoked his diplomatic immunity and refused to testify.