Walter F. Mondale's presidential campaign acknowledged yesterday a violation of federal campaign spending laws, and the House ethics committee said it had found that his running mate, Rep. Geraldine A. Ferraro (D-N.Y.), technically violated the Ethics in Government Act at least 10 times since 1978 by failing to file information about her family's finances.

Mondale's campaign agreed to pay the U.S. Treasury $379,640 plus a civil fine of $18,500 for accepting the excess donations through his delegate-selection committees, which were units set up ostensibly to finance the campaigns of Mondale supporters who were running for delegate seats at the July Democratic National Convention.

Mondale had ordered the committees to disband in late April under pressure from one opponent, Sen. Gary Hart (D-Colo.), and promised to refund several hundred thousand dollars to union political action committees and individuals who had given the legal maximum to his campaign. Instead, the campaign will pay the money to the U.S. Treasury.

Details of the agreement became public yesterday after the Federal Election Commission sent copies to parties in the dispute. The closed-door FEC vote was 4 to 2. The commission agreed to close the case and take no further action against any of the individuals or unions involved.

The House Committee on Standards of Officials Conduct voted 8 to 2 Monday to approve a 47-page staff report accusing Ferraro of technical violations of House ethics rules that do not require disciplinary action.

Ferraro, who could not seek reelection when she became the Democratic vice-presidential nominee, will not be subject to House jurisdiction when her term expires Jan. 3.

In a statement released with the report, ethics committee Chairman Louis Stokes (D-Ohio) and Floyd Spence (R-S.C.), the ranking minority member, criticized as "totally inaccurate" a report in Tuesday's Washington Times that called the committee vote a "technical reprimand."

Stokes and Spence said that although the committee found that Ferraro had committed technical violations, "No information received by the committee staff . . . indicates a deceptive intent on the part of Rep. Ferraro. Instead, all the facts point to error, oversight, and misinterpretation as the reasons for the incomplete disclosures."

Speaking to reporters outside her office, Ferraro criticized the account in The Washington Times and said, "The committee's lengthy investigation, in which my husband and I and my attorneys fully cooperated, has uncovered no failures and mistakes on my part with respect to disclosure of my own financial affairs."

She said a key finding of the committee was that "in no instance did I act with intent to deceive. That finding confirms me in my belief. . . that I never acted in a manner inconsistent with my public trust and responsibility."

The committee concluded that Ferraro was not justified in claiming that the business dealings of her husband, New York real estate dealer John A. Zaccaro, were exempt from public disclosure.

Ferraro claimed that Zaccaro's holdings were exempt because she had no knowledge of them and did not benefit from them. But she acknowledged during her vice-presidential campaign that she was an officer and stockholder in P. Zaccaro Co., the firm her husband headed. She also said she received income from the firm.

Stokes and Spence said Ferraro met none of the three tests needed for a member of Congress to exempt a spouse's holdings from disclosure. The tests require a member to have no detailed knowledge of a spouse's assets, have no role in their creation, and derive no benefit from them.

They gave examples of items characterized as Zaccaro's financial interests, including "maintenance of the Forest Hills home, education of the children and the purchase of vacation properties." But they added that "the exemption's proper use is clouded with some amount of ambiguity."

Ferraro said, however, that she continues "to believe my exemption claims were reasonable and proper."

If the committee had recommended disciplinary action, Ferraro would have had 21 calendar days under House rules to answer any finding of alleged violations. Then the House would have had to meet in special session to consider disciplinary action.

The two dissenting committee votes were cast by Reps. Hank Brown (R-Colo.) and James V. Hansen (R-Utah), who said they felt that the committee should have recommended stronger action against Ferraro. In a dissenting opinion, Brown charged that disclosure of "Zaccaro's financial interests has not been made" and said the committee should have held hearings on that question.

During its investigation, the committee obtained copies of canceled checks from a Ferraro-Zaccaro checking account to prove that Ferraro benefited from her husband's income.

Committee investigators were unable to account for 463 canceled checks in amounts of $1,000 to $22,078 from the joint checking account from 1978 to 1983, the report said.

The report drew no conclusions about the missing checks and does not indicate whether the checks were subpoenaed or whether Ferraro was asked to account for the missing checks.

The committee of six Republicans and six Democrats began its investigation Sept. 12 in response to a complaint by the Washington Legal Foundation.