President Reagan defended his foreign policy yesterday against charges of disarray and belligerence, but at the same time repeated earlier stands on limited nuclear war in Europe and the Saudi Arabia Mideast peace plan that have generated trouble overseas.

Reagan also said that "so far I've had no answer" to the disagreement last week between Secretary of State Alexander M. Haig Jr. and Secretary of Defense Caspar W. Weinberger over whether a nuclear weapons "demonstration shot" is part of North Atlantic Treaty Organization strategy. Later the White House said Reagan actually had the answer, but chose not to disclose it.

In his fifth news conference at the White House, Reagan said, "We are not in disarray with regard to foreign policy. I think our accomplishments have been rather astounding."

As evidence, he cited 70 meetings he has had with foreign leaders in various areas, claimed that the U.S. relationships with Canada and Mexico are better than ever and that those with European allies have never been stronger, and said "we've progressed" in the Middle East.

His language was very general and his references sometimes unclear. He gave no details on his claims of success or most other points he addressed in the foreign field.

The president, who summoned Haig and White House national security adviser Richard V. Allen to an hour-long discussion of foreign policy operations last Thursday, said his aim had been "to find out" and to insure "that we're a little more careful." The meeting followed Haig's charge that a top White House official, whom he did not name, has been waging an extended "guerrilla campaign" against him.

Reagan drew laughter from reporters when he said, "There is no animus, personal animus and there is no bickering or back stabbing going on. We're a very happy group."

Asked about hints of possible U.S. intervention in Central America and the Middle East, Reagan said, "We have no plans for putting Americans in combat any place in the world, and our goal is peace."

He charged that the conflict in El Salvador results from "exported revolution . . . expansionist policy" of the Soviet Union and Cuba. He described U.S. efforts as mostly economic and said, "I don't believe this requires in any way, nor have we considered, aid of the kind of actual military intervention on our part."

Reagan did not address reports that Egypt was promised a U.S. military umbrella last month in case of an attack on Libya, despite two questions referring to the reports.

In words that may reverberate abroad, Reagan repeated his stand that battlefield nuclear warfare in Europe would not necessarily bring on an exchange of strategic nuclear attacks by the United States and the Soviet Union. His statement along these lines in an Oct. 16 interview with out-of-town editors stirred a storm in Western Europe, where U.S. strategy for nuclear war is at issue in political debate and street demonstrations.

"There's high risk, there's no question of that," said Reagan, referring to the use of battlefield nuclear weapons. He said his Oct. 16 statement had been offered only as a possibility "and I think you'd still have to say that that possibility could take place."

Haig touched off the controversy about a demonstration nuclear shot in Europe with testimony last Wednesday that "there are contingency plans in the NATO doctrine" for such a blast. The following day Weinberger testified that "there is absolutely nothing in any of the plans with which I am familiar that contains anything remotely resembling this, nor should it."

Late Thursday the administration sought to resolve the contradiction by saying that such a demonstration is "a possible option" but is "no precise NATO military plan." Reagan's remark that "confusion" exists on the issue and "so far I've had no answer" seemed to resurrect the dispute.

White House deputy press secretary Larry Speakes told reporters after the news conference that Reagan actually does not expect an answer. The president knows what is in contingency plans, said Speakes, but "he wasn't going into contingencies."

Positive comments by Reagan and Haig two weeks ago about elements of Saudi Arabia's eight-point Mideast peace plan brought sharp protests from Israeli Prime Minister Menachem Begin, who calls it a plan "to liquidate Israel." After the Israeli protests, U.S. officials refused to repeat the earlier comments or to say anything substantive about the Saudi plan. Reagan yesterday said that, though the matter is in "some dispute," he believes the recognition of Israel as a state is implicit in one point of the plan. This, he said, could be incorporated in American diplomacy, as well as "the other point"--actually, the same one he had just described--calling for all states in the region to live in peace.

On another subject, Reagan defended the plan to build the B1 bomber as necessary to U.S. defenses, and said a Congressional Budget Office cost estimate of $39.8 billion is "a worst-case" estimate he does not accept.