President-elect Ronald Reagan, declaring his intention to confront Soviet leaders in negotiations with their "policies of agression" throughout the world, began sketching in his plans yesterday for the foreign policies of his adminstration.

In a news conference in Los Angeles and an interview published in Time magazine, Reagan made plain his desire to follow a policy that is more assertive, but also more consistent, than that of the Carter administration in relations with the Soviet Union.

Reagan said nothing in either the news conference or the magazine interview of a cooperative side of the relationship with the Soviets, a facet of the superpower link that had been stressed at the beginning of all recent U.S. adminstrations, though it sometimes faded at the end.

Soviet statements since the election have avoided personal attacks on Reagan, although the new Soviet premier, Nikolai Tikhonov, made a tough speech yesterday assailing "American imperialism" in general. The president-elect's statements are likely to bring sharp reactions from Moscow, according to career U.S. government specialists, especially because they can no longer be discounted as campaign oratory.

"I believe in linkage," said Reagan to reporters in Los Angeles, referring to the concept of the Nixon-Kissinger era that negotiations to limit U.S. and Soviet strategic arms should be linked to the resolution of political issues between the superpowers throughout the world. The Soviet Union never accepted this idea, and in practice the arms negotiations have been separated to some extent from regional disputes between the two most powerful nations.

Reagan volunteered at his press conference that "the policies of aggression of the Soviet Union . . . must be a part of discussions and negotiations that go forward" with the Russians. He added, "I don't think you simply sit down at the table to discuss arms limitations, for example, but you discuss the whole attitude, world attitude, as to whether we're going to have a world of peace or whether we're simply going to talk about weaponry and not bring up these other subjects."

In the Time interview Reagan said "their overall policy of aggression must be a part of what is going on at the negotiating table." Asked why he believed he would succeed with such an approach, which did not work in the past, Reagan replied that if the Soviets did not go along, "maybe the disadvantage [to them] would be that you wouldn't negotiate."

Reagan also told Time that he will make plain to the Russians "right away" that "we have to renegotiate SALT II," the strategic arms limitation treaty signed by President Carter and Soviet President Leonid Brezhnev in June 1979. He repeated his plan to "take what is usable out of SALT II" as the basis for renewed discussions.

To a question about the probable Soviet reaction to his views of Salt and other issues, Reagan said he believes that the Russians prefer consistency to "the vacillation of our recent foreign policy," even if this means dealing with "someone who is firmer, someone who opposed some of the things they did -- who let them know what they were dealing with."

Reagan's approach to foreign policy has been shrouded in suspense and speculation because of his lack of experience in this area, the confrontational rhetoric that he has often used without elaboration of the potential consequences and the unusual degree of uncertainty about who his key advisers are likely to be.

While Reagan's statements about the Russians were unconventional for a president-elect, the interim foreign policy advisory board he named yesterd is composed mainly of persons who have been officials of previous adminstrations or foreign policy makers in Congress. While most of them are considered tough on the Russians, none is a spokesman for the "radical right" groups backing Reagan, which are outside the board mainstream of foreign affairs thinking.

The sudden and recent prominence in the Reagan camp of former secretary of state Henry A. Kissinger has generated speculation about a return of the diplomatic superstar to an active public post.

Reagan ducked a news conference question about whether Kissinger might be his secretary of state.But in the Time interview, which was completed before the election, Reagan seemed to rule this out, saying that "he [Kissinger] has made it very plain that he does not want to be part of the adminstration" but would be available for "missions or something of that kind."

In his press conference and interview Reagan addressed a number of other foreign policy issues in ways that suggested, at least, tendencies and general directions.

Especially in regard to the pending attempt to negotiate the release of the 52 Americans held in Tehran, Reagan was careful to state that Carter has the authority and responsibility until January 20, Iauguration Day. "We are not going to intrude," Reagan told the news conference.

Only once did he seem to verge on becoming involved in the current situation. Apparently referring to reports from Tehran that his election might delay the release of the hostages, Reagan admonished Iran not to have "any ideas there will be profit to them in waiting any period of time" before returning the Americans. He added, with a notable hardening of his voice, "We want those people home."

The president-elect displayed awareness of the sensitiveness of contacts with foreign leaders in this period of transition. Asked if he plans to meet Israeli Prime Minister Menachem Begin, who will be in the United States next week, Reagan replied, "There's a delicate point here" that presents a risk of "putting yourself in a position that's not yet mine, the presidency."

Israeli Ambassador to the United States Ephraim Evron is flying to Los Angeles today "to establish lines of communication" in the Reagan camp, the Israeli Embassy said yesterday. But a spokesman said Evron did not expect to see the president-elect, and that Begin is not asking to meet Reagan when he comes here next week.

Regarding issues in the Middle East, Reagan in his news conference repeated his earlier assertions that the Palestine Liberation Organization (PLO) is "a terroist organization," a position that he Carter adminstration has usually avoided because of Arab backing for the PLO as spokesman for the Palestinian people.

Reagan said he would do whatever he could to promote peace in the Middle East but volunteered, evidently in deference to Israel, that "we don't intend to mandate or dictate a settlement." In the Time interview Reagan stressed the role of King Hussein of Jordan in advancing a Mideast settlement, and said he hoped for an early meeting with Hussein.

The Los Angeles news confernce, which was televised nationally, presented Reagan with a wide range of questions on foreign topics, from Latin America to Northern Ireland, France and Turkey. He handled all the questions without difficulty, usually making only very general comments on grounds that details are yet to be settled.

The final question of the press conference, regarding his stand on human rights abroad, signaled a turn away from the policies of the Carter adminstration. While expressing a belief in human rights, Reagan went on to criticize the turning away from "basically friendly" countries because of disagreement on "some facet of human rights" only to find that "the result was that they had lost all human rights in that country." This is likely to be read abroad as suggesting a far less vigorous U.S. role in pressing human rights cases among friendly nations.