After seven months of deliberation, the federal Gold Commission tentatively voted yesterday against a return to the gold standard, a move some of President Reagan's supply-side supporters insist is the only way to bring down interest rates and inflation.

The commission's preliminary vote came just days after the Reagan administration, in the president's economic report to Congress, said "The evidence does not suggest that the gold standard achieved greater stability in price levels or growth." Most economists oppose a return to a gold-backed dollar.

However, the commission did agree tentatively that Congress and the Federal Reserve should study the merits of some kind of money rule--albeit not gold-linked--in order to slow the growth of money and ensure a steady reduction of inflation.

It also voted in favor of creating a new gold coin--perhaps called an American Eagle--to be sold by the Treasury Department at a small markup over the gold price.

The commission, in its draft proposal, recommended that the gold coin be exempt from capital gains tax and sales taxes, but not be legal tender and have no dollar denomination.

The 17-member commission, chaired by Treasury Secretary Donald T. Regan, has to send its final report to Congress at the end of March. The commission was created by a 1980 act of Congress to study the potential role of gold in the money system, but it only began work last July after its members were appointed by Reagan. Commission meetings were opened to the public after its first meeting last year, after protests from gold supporters that the commission was trying to bury the issue.

A final draft incorporating yesterday's decisions is to be considered at a meeting on March 12. There was some confusion yesterday about precisely what language had been adopted amid a welter of amendments to the draft recommendations.

At one stage Rep. Henry S. Reuss (D-Wis.) walked out in protest at a decision of the chair. As the commission includes some fervent advocates of a return to the gold standard and some equally fervent opponents, its sessions have often been stormy.

However, Jerry Jordan of the president's Council of Economic Advisers expressed pleasure yesterday at a "remarkable convergence" in the end "around the gold coin and the money rule" study.

Henry Wallich, a member of the Federal Reserve Board, argued against the recommendation that Congress and the Fed study a money rule and other possible improvements in money management.

He said that the commission was not set up to study the whole of monetary policy and would be exceeding its charter if it told Congress to study a rule. Monetarists tend to favor such a rule, which would lay down how much the money supply should be allowed to increase, rather than leaving it up to the Federal Reserve to determine.

A majority of the commission agreed that the key to long-run price stability was steady growth in the nation's money supply.

The new gold "coin" would be more like a medallion, according to Glen Kirsch of Deak-Perrera, as it would not be legal tender. However, the recommendation to exempt the coin from taxes would make it "something special," one of the commission members said.

The tax-exempt status could make the coin a better buy than gold coins minted overseas, such as the Kruggerand or Canadian Maple Leaf. If Congress adopts the idea, it would be up to the Treasury to set the price and to decide how much gold to sell in this form.

The commission also adopted a draft recommendation in favor of revaluing the nation's gold stock at market prices over a number of years. This would have the effect of greatly increasing the value of the Treasury's gold assets.

However, the government should not use this extra paper wealth to finance spending, the commission members agreed.

A supply-sider, Rep. Jack Kemp (R-N.Y.), who has urged a return to a gold standard, said he was "disappointed" by the commission's recommendation but had expected it. A majority of the commission members had been opposed to a return to gold all along, Kemp said.

But Kemp added, "The issue is not dead . . . . The poor performance of the economy and the decline of the financial markets" would force the president to reevaluate money policy and to turn toward gold in the next few months.

Opponents of a return to the gold standard argue that it is impracticable, would not improve money management and would lead to greater rather than lesser instability in financial markets.