President Reagan, emerging from pre-summit isolation, Friday appealed to Soviet leader Mikhail S. Gorbachev to enter the Western "house of democracy" by embracing the values enshrined in the 1975 Helsinki agreement.

Sounding the human rights theme he will stress in their talks in Moscow, Reagan praised Gorbachev's "glasnost" and the openness that has flourished in his three years at the Kremlin helm.But while dissidents are released from labor camps and books and movies criticizing the communist system gain currency, the president said, "Soviet practice does not - or does not yet - measure up to Soviet commitment."

In the 1975 accord with 34 other nations, the Soviets pledged to provide more liberty for their people and those in Eastern Europe. And yet, 13 years later, Reagan said, the cases of divided families and blocked marriages remain on the East-West agenda, while Russians trying to emigrate are subjected to artificial quotas and arbitrary rulings.

"And what are we to think of the continued suppression of those who wish to practice their religious beliefs?" the president asked.

Reagan spoke in a prepared speech to a Finnish audience in Finlandia Hall, where the Helsinki Final Agreement was signed in 1975.

He said he welcomed every sign that the Soviets and their allies are ready to adopt Western values.

"The house of democracy is a house whose doors are open to all," Reagan said.

As he spoke, Jewish groups gathered in the Finnish capital to mount public pressure on Moscow in behalf of Sovie Jews waiting for exit permits and those seeking wider latitude to teach and practice their religion.

A Friday evening Sabbath service was planned outside a Lutheran church in an ecumencial display of unity.

Before the speech, Reagan and his wife, Nancy, had lunch with Finnish President Mauno Koivisto.

As photographers spun into action, Mrs. Reagan plucked yellow daisies from the luncheon flower arrangement. The president proudly wore one as a boutonniere and Mrs. Reagan pinned one on Koivisto's lapel.

Reagan played down the significance of the Soviet decision to cancel one of his meetings with Gorbachev. "We only had four meetings at our summit in Washington," he told reporters. "We have to recognize that their government has normal business that has to be conducted and we have to schedule accordingly - that's what we did when the summit was in our town."

Asked if he thought there was anything more important than his visit with the Soviet leader, Reagan said, "I don't think there's anything more important as far as I'm concerned, but they have business to do."

The president, responding to questions about Soviets objections to some of the people he planned on meeting with in Moscow, responded simply, "We do the best we can."

In other summit-related developments.

-A top Soviet arms control official in Moscow called on the United States to speed up negotiations on a treaty to cut long-range nuclear arsenals by making good on promises of compromise.

Viktor Karpov, head of the Soviet Foreign Ministry's arms control department and a former chief negotiator at Geneva arms talks, told the Tass news agency the United States had agreed to compromise on several key issues, but then backed off.

"As soon as an issue reaches the American delegation in Geneva, it gets stuck there," he complained.

- And an aide to Gorbachev charged that the United States is violating a peace accord by continuing to ship arms to Afghanistan's anti-communist Mujahedeen guerrillas.

"They are arming, quite openly, those who want to go on in their civil war," said Yevgeny Primakov, who is head of the Institute for the World Economy and has acted as a key adviser to Gorbachev on Afghanistan.

The 1975 Helsinki agreement signed by the United States, Canada and 33 European nations including the Soviet Union initially was viewed skeptically by American political conservatives because it implicitly accepts East European boundaries set after World War II in Moscow's favor.

But in the years since, the Helsinki agreement has served as a Western platform for chastising the Soviets for deficiencies on human rights.

Meanwhile, in Washington, the U.S. Senate Friday moved toward ratification of the historic treaty that Reagan and Gorbachev signed at their December summit eliminating medium range nuclear missiles. (See story on this page.)

Senate leaders said they had the votes to approve the pact. White House Chief of Staff Howard H. Baker Jr. was set to rush the treaty to the president for a ceremonial exchange of the ratification documents with Gorbachev.