President Reagan met for 40 minutes yesterday with new Soviet Ambassador Yuri Dubinin, who presented him with a letter from Soviet leader Mikhail Gorbachev that a senior U.S. official described as "generally positive" on arms-control issues.

The White House press office issued a terse statement after the meeting, describing it as "cordial and businesslike." Officials gave no details other than to say that Gorbachev's letter did not contain proposed dates for a summit that Reagan is seeking in the United States after the November elections.

Earlier in the day, the president again sounded words of conciliation to the Soviets following the theme of his speech in Glassboro, N.J., last week, in which Reagan said the Soviets were making "a serious effort" to negotiate a reduction in nuclear arms.

In an interview with the Los Angeles Times, the president declined to rule out U.S.-Soviet negotiations that would trade deployment of the Strategic Defense Initiative, commonly called "Star Wars," for Soviet reductions in offensive nuclear weapons. Reagan said that "whatever way is necessary to get an agreement, we'll do" it.

The president praised SDI as a defensive system that would be of value to both the Soviets and the United States, and insisted that continued research was important. But when asked whether deployment of SDI, which would require changing the 1972 Antiballistic Missile Treaty, was negotiable, he replied, "That's right, yes."

The latest Soviet proposal at the nuclear arms talks in Geneva calls for the United States to remain in compliance with the ABM Treaty for 15 more years.

In the interview with Jack Nelson, Eleanor Clift and Joel Havemann of the Times, the president also declined to repudiate unequivocally the 1979 SALT II arms-control treaty, despite a statement last week by White House spokesman Larry Speakes that the limitations included in this unratified pact are no longer in effect.

Asked if the treaty were "dead," Reagan said, "I am just reluctant to come out with some of the declarations that many of you want to hear, either way, because, in a way, you commit yourself in advance to things that may become issues in a negotiation."

Last month Reagan ordered dismantling of two Poseidon missile submarines to keep the United States in compliance with treaty limits, at least temporarily. At the same time he announced that, in response to Soviet violations, the United States was prepared to exceed the treaty's limits later this year when additional B52 bombers are scheduled to be equipped with air-launched cruise missiles. However, Reagan said he would "take into account" any changes in Soviet behavior at the negotiating table in Geneva and in compliance with the treaty in the interim.

Since then, he has called on Gorbachev to honor a promise made at their Geneva summit last U.S. officials want summit to occur after elections. November: that the Soviet leader would come to the United States for a second summit this year.

In his interview yesterday, the president was asked if there would be a summit this year. He replied, "I believe so, and he Gorbachev has given every indication that he wants to have a summit."

Reagan went on to say that he was waiting to see if Gorbachev "has a particular date that he could suggest." U.S. officials want the summit to occur in November or early December, after the U.S. elections.

Despite Reagan's hints of a willingness to negotiate SDI deployment, Defense Secretary Caspar W. Weinberger continued to insist yesterday that the missile defense system is not a bargaining chip.

Speaking to the U.S. Space Foundation, a private organization supporting space research, Weinberger said of SDI: "I think the president is firmly committed to it." He added that SDI held a high priority for the president and said Reagan "is not putting it forward as something to be given away."

Asked if its deployment were negotiable, Weinberger replied: "Nothing should hamper or delay in any way our ability to deploy a strategic defense system should the research prove, as I believe it will, feasible."