A Libyan jet that fired on a U.S. Navy warplane last week may have been on a "targeted mission," Secretary of State Alexander M. Haig Jr. said yesterday, and he added that he did not believe the firing was a spur-of-the-moment decision by the pilot.

The Libyan pilot clearly announced that one of the two Libyan aircraft had released a missile, Haig reported, adding that he was "not one who believed that these operations . . . are not pretty carefully managed and controlled."

Haig, in his appearance on "Issues and Answers" (ABC, WJLA), talked about "tapes that have been revealed." No tape recordings of the in-flight dialogue have been released, though Pentagon officials have told reporters privately about them and there are indications some kind of transcript may be made public soon.

The Pentagon is anxious to put to rest any allegations that the United States may have deliberately provoked the Libyans to fire in order to send a clear warning to Libya's revolutionary ruler, Col. Muammar Qaddafi. Libya claims its planes were attacked by eight U.S. Navy fighters. The two Libyan jets were downed by missiles from U.S. Navy F14s in the incident over the Gulf of Sidra in the Mediterranean last Wednesday.

Later in the program, Haig said the possibility that the Libyan firing was an accident could not be discounted, but that he believed it was a "testing incident" because of other episodes over the last five years where Libyan aircraft have engaged in what Haig called harassing and provocative actions.

The secretary did not answer directly a question of whether he had ever told people off the record that Qaddafi was "a cancer that had to be removed."

But, he said, "I've made no bones about the concerns I have, and I know the president feels, of the lawlessness which has characterized Qaddafi's international behavior." As examples, Haig listed Qaddafi's support for terrorism abroad, including this hemisphere; his "blatant" invasion of neighboring states, and efforts to subvert and replace governments along his border.

Calling such behavior unacceptable, Haig said the international community can no longer overlook "these illegal acts whether they come from Libya, Cuba or the Soviet Union. The time has long since passed when the free world and the United States as its leader must stand up and be heard on this issue."

The United States was not naive and anticipated that there could be trouble in the Gulf of Sidra, Haig said.

The president had personally approved the naval exercise that involved two aircraft carriers and their support ships and the rules of engagement, and while the rules were the standard guidelines, President Reagan, Haig said, "had strongly reaffirmed" them beforehand. Those rules are to fire back if fired upon.

Haig said presidential counselor Edwin Meese III was "exactly right" in the decision to wait some six hours before waking the president to tell him of the incident. Haig said he and Meese both concluded at the time that until more was known, it was "not worthwhile" to notify Reagan.

During the network program, Haig sought to portray the administration as in considerable philosophical harmony on other questions as well, including crucial decisions facing Reagan on new strategic nuclear weapons such as the MX missile and B1 bomber.

The secretary went out of his way to praise Defense Secretary Caspar W. Weinberger, claiming that in the five administrations that Haig has served: "I have never seen a case where in a brief period of seven months a secretary of defense has pulled together such a comprehensive approach and package for the president to consider."

Haig said the president is considering his strategic options and that "I think we are all best served in this administration and, frankly, in the press to reserve any judgments until the president makes these decisions." At various times, White House aides, military officials and Haig himself have been reported unhappy with some of the choices Weinberger has seemed to favor.

The former four-star general said he had always supported the so-called triad of land-based missiles, submarine-based missiles and bombers for America's strategic retaliatory force. "I feel confident," he added, "that the ultimate mix the president approves will have those fundamental characteristics."

Haig's comments seem to indicate that the White House will have some form of new land-based missile in its strategic package, though Haig did not address the crucial and controversial question of how it would be based.

The administration is known to be backing away from an earlier Weinberger idea for an immediate start on an airborne verison of MX and is considering a scaled-down, land-based plan for MX deployment and a so-called common missile for use by the Navy and Air Force.

On the forthcoming battle over administration plans to sell five early warning radar planes to Saudi Arabia, Haig said the administration "intends to proceed and we intend to win" in Congress.

He said Israeli opposition and concerns are understandable and that the United States is prepared to discuss ways to maintain Israel's qualitative edge over potential foes.

Haig said he hoped his meeting next month in New York with the Soviet foreign minister, Andrei Gromyko, the first ministerial meeting between the two, would eventually lead to other such meetings and ultimately to a summit between Reagan and Soviet President Leonid I. Brezhnev.