The Securities and Exchange Commission charged yesterday that Grumman Corp. deceived shareholders by failing to disclose that certain corporate maneuvers, including the use of a Grumman employe pension fund to buy the company's stock, were designed to fend off a proposed takeover by LTV Corp.

The SEC yesterday asked a federal court to enjoin Grumman from further violations of proxy and tender offer sections of federal securities laws and asked for a court order requiring Grumman to disclose what the SEC said it had not disclosed. A Grumman spokesman said the company denied the SEC's charges.

The SEC's complaint was the latest complication in a fiercely fought takeover battle waged on several fronts since LTV announced its $450 million takeover bid on Sept. 23. The merger proposal, which has been extended until Nov. 20, would combine two major defense contractors.

Earlier in the fight, Grumman won a temporary injunction barring the LTV takeover, a ruling that is being appealed. In a development related to the SEC charges, the Labor Department filed a suit last month against trustees of the Grumman pension plan for using pension fund assets to buy Grumman stock as part of the strategy to block the takeover bid. The Federal Trade Commission also has sought to bar the takeover on antitrust grounds.

The SEC charged yesterday that Grumman failed to disclose that purchases of its stock by Grumman and by the Grumman pension trust were aimed at blocking LTV. The company also failed to disclose that the same motivation was at the heart of a request by Grumman to the Madison Fund, an investment company, to purchase Grumman stock, the SEC said.

According to the SEC, on Oct. 7 Grumman's directors amended the agreement and declaration of trust for the pension trust to indemnify pension trustees from liability or expenses rising from their acts as trustees. Then the trustees voted to reject LTV's offer of $45 a share for Grumman stock held by the pension fund.

The trustees wrote the SEC on Oct. 13 that the pension trust might purchase up to 1.275 million shares of Grumman, calling it "an attractive beneficial investment for the pension trust at this time" and indicating that there was no particular plan for disposition of the stock. The company should have disclosed that the purpose of the purchases was to "defeat the LTV tender offer," the SEC said.

The pension fund--which had bought no Grumman stock since at least 1973--bought the stock at prices ranging from an average of $36.622 to $38.6146 a share, according to the SEC.

The trustees are Grumman Chairman and Chief Executive Officer John C. Bierwirth, Senior Vice President Robert G. Freese and Grumman Aerospace Corp. Senior Vice President Carl A. Paladino. LTV has charged in papers submitted in one of the court battles surrounding the takeover attempt that the three were named trustees, replacing an independent trustee, as part of an overall strategy to block any takeover attempt.

The SEC also said that the company should have said in a notice that the company itself might buy stock and that the prospective purchases were for the same purpose--to defeat LTV's takeover bid. Shareholders also should have been told "the facts and circumstances concerning the request by Grumman of Madison Fund to purchase a substantial position in Grumman stock to aid Grumman in its efforts to frustrate LTV's tender offer" and about the indeminification of the pension fund trustees, the SEC said.

A Grumman spokesman said that the company denies the SEC charges. "We didn't violate any securities laws," said Sandy Jones. "Our disclosures were complete and proper," he said.