Secretary of State Alexander M. Haig Jr. forced the new director of the Arms Control and Disarmament Agency to cancel a meeting with Soviet Ambassador Anatoliy F. Dobrynin last month just two hours before it was to take place. Haig felt there had been inadequate preparations for the meeting, according to administration sources.

After Haig satisfied himself that the message ACDA director Eugene V. Rostow proposed to carry to the Soviets was appropriate, Rostow was permitted to reschedule the meeting.

But by then he had to settle for Dobrynin's principal deputy, Alexander A. Bessmertnykh, because Dobrynin had left for vacation.

This was the first blatant sign of disagreement between Haig and Rostow over who will dominate arms control policy. But, according to administration sources, it is only an indication of the contest under way within a group of strong-minded men who share pieces of the responsibility for this controversial area.

Officials close to both Haig and Rostow declined to speak in any detail yesterday about the episode. It was understood that the Haig camp believed Rostow had rushed into the meeting with Dobrynin without getting approval from Haig and other top officials.

The Rostow camp, it is understood, felt there had been thorough preparation and approval for the meeting. But they believe Haig did not realize this, and ordered the meeting canceled when he learned of it. This version is rejected in the Haig camp.

Reached by telephone, Rostow minimized the incident, and said he and Haig had worked out the problem harmoniously.

There was also disagreement within the two camps about the purpose of the meeting. According to a senior ACDA official, it was intended to begin a dialogue with the Soviets, and especially to counter the current "Soviet propaganda campaign" to the effect that the Reagan administration is interested only in building, not controlling, arms.

According to the official, Rostow told Bessmertnykh that the administration is interested in significant arms control. But he added that the superpowers would have to find new means beyond their spy-in-the-sky satellites to verify any future agreements on control of the destructive power of weapons as well as the quantity of missile launchers.

At the State Department, the Rostow meeting was described as exploratory, not a separate channel for negotiations, and one that was not expected to have specific result.

It was pointed out that the ACDA director had not met with any senior Soviet official in his new job.

Until now the only direct American contact with the Soviets on arms control issues has been in meetings between Haig and Dobrynin.

Haig is scheduled to meet Soviet Foreign Minister Andrei Gromyko twice later this month in New York. A principal item on their agenda is to explore possibilities for new negotiations to control nuclear weapons in Europe.

Discussing the Rostow-Haig relationship, a State Department spokesman yesterday noted that under the 1961 law establishing ACDA, the agency director's activities and all his dealings with representatives of other nations were to fall "under the direction of the secretary of state."

The State Department, he said, "has and will continue to take the lead in this administration, coordinating policy required to prepare for and support the conduct of arms control negotiations."

Rostow, a Democrat and former undersecretary of state in the Johnson administration, when the arms control agency dominated all policy-making in this field, came to Washington planning to reassert ACDA's primacy.

A source close to Rostow reiterated yesterday that, in time, ACDA would reestablish the preeminent position it once held. However, ACDA officials also acknowledged the leading role of Haig under the arms control statute.

By the time Rostow took his new job in late June, the two principal fields of arms control, strategic arms negotiations with the Soviets and possible discussions over so-called "Theater Nuclear Forces" in Europe, had been divided between the State Department and the Pentagon.

Haig had taken control of the interagency apparatus that manages strategic arms control policy, and had delegated day-to-day authority to Richard R. Burt, a former New York Times reporter who is director of politico-military affairs at State.

In the Pentagon assistant secretary Richard Perle and his boss, Fred C. Ikle, the under secretary of defense for policy, had assumed the preeminent role in deliberations over the theater nuclear weapons issue.

Ikle was ACDA director in the Nixon and Ford administrations. Perle, a former aide to Sen. Henry M. Jackson (D-Wash.), has been a prominent critic of the arms control efforts of the Nixon, Ford and Carter administrations.

Assistant Secretary of State for European Affairs Lawrence S. Eagleburger was designated chairman of one group preparing for the TNF negotiations, while Perle chairs another committee which will decide how many weapons will be involved.