Paul C. Warnke, President Carter's choice to head the Arms Control and Disarmament Agency, told his critics inside and outside a Senate hearing room yesterday that he rejects the labels they've tried to attach to him.

In almost four hours of cool testimony, Warnke answered charges from the right that he would be too soft in arms talks with the Russians by stressing his support for a strong national defense and opposition to unilateral disarmament.

"If anyone thinks I represent a fixed position," Warnke told the Senate Foreign Relations Committee, "then some of them will be surprised and some will be disappointed."

Warnke denied that he has any preconceptions on arms control and added:

"I believe very strongly that there is promise in arms control . . . Promise for our national security.

Sen. John C. Danforth (R-Mo.) early in the hearing asked that former Deputy Secretary of Defense Paul Nitze be called to give "the other side of the coin" from Warnke.

"It seem to me that we are really voting for a philosophy" when voting on Warnke, Danforth said.

Nitzke, as several senators pointed out, had not sought to appear before the committee on Warnke's nomination, but he wrote a letter for the record that said Warnke may not "be a qualified student or competent judge" of weapons capability and strategy.

Opponents of Warnke also were examining whether he had anything to do with the leak of the Pentagon Papers.

Warnke said he neither knew that Daniel Ellsberg had requested access to his copy of the papers nor had any reason to believe Ellsberg would leak them to the press.

Warnke told the committee that he "will do my best . . . to argue persuasively for arms control initiatives where I believe they are warranted" and to "seek ways to head off new explosions of arms technology . . ."

And, he expressed the conviction that the issues which now block talks with Moscow - the Soviet Backfire bomber and U.S. cruise missile development - "can be resolved in a manner fully consistent with U.S. national security interests in a reasonable short period of time."

Warnke supporters on the committee, Sens. Hubert H. Humphrey (D.-Minn.), Jacob K. Javits (R-N.Y.) and Joe Biden Jr. (D-Del.), stressed to his foes that Carter, not Warnke, will set arms control policy.

"Arms control and disarmamrny policy, being an important part of foreign policy, must be consistent with national security policy as a whole," Warnke said quoting from the Congress' words in creating the ACDA, and he noted that his colleague, Secretary of State Cyrus R. Vance, might be displeased if he began to elaborate a policy.

"I will be part of a team," Warnke said.

Warnke said he considered close consultation with Congress an essential part of arms control negotiation and that he would be willing to consider having congressional representatives on his negotiating team in Geneva if he is confirmed.

As ACDA director and chief arms control negotiator at the Geneva talks with the Russians, Warnke said, he would divide his time between Washington and Geneva. Therefore, he told the committee, he would need a very strong deputy to act in his absence here.

Warnke told the senators, much of whose questioning consisted of reading past Warnke statements from earlier testimony and writing, that he has always been prepared to change his mind.

On one point that has aroused Warnke critics, the 57-year-old lawyer appeared to give up, at least for the immediate future, a tactic he has advocated.

He defended the idea of "parallel restraint" in which the United States might announce a freeze on one aspect of weapons development and await a counter move by the Soviet Union. Warnke noted that President Kennedy in 1963 use this technique to initiate the process that led to a ban on atmospheric testing of nuclear weapons.

However, Warnke said that "in a negotiating context" he would not recommend this technique. If the two nations are talking, Warnke said, then any potential freeze should be part of the whole package.

At the bargaining table one negotiator should say: "What would you do if I did such and such," Warnke said, and then the response would be monitored.

Warnke's nomination drew generally favorable comments from Foreign Relations Committee members who are expected to approve his nomination by a large majority.

Only Sens. Robert P. Griffin (R-Mich.) and Danforth mader serious attempts to question Warnke's suitablility. Griffin said he was troubled by possible conflicts fron the two hats Warnke would wear as negotiator as welI as ACDA director.

A friendly senator, Frank Church (D-Idaho), walked Warnke gently through the Pentaon Papers incident early in the hearing.

The copy Ellsberg used to make the papers public was one Warnke, an assistant secretary of defense under President Johnson, had sent to the Rand Corp. for safekeeping because he had no classified storage facilities after leaving office.

Warnke, Morton Halperin and Leslie Gelb had access to the copy and any two could authorize access for another person with the proper clearance, Warnke said. Gelb, now director of the State Department Bureau of Politico-Military Affairs, and Halperin authorized Ellsberg's access to the copy, Warnke said.

Ellsberg had a top-secret clearance at the time. "I thought the security requirements were adequate," Warnke said. "The security requirements were not inadequate; they were not abided by."

The retired chief of the Defense Intelligence Agency, Lt. Gen. Daniel Graham, and Penn Keble, executive director of the Caolition for a Democratic Majority, and other witnesses will testify today when the hearings resume. The coalition composed a four-page memorandum critical of Warnke.

Warnke said yesterday the memorandum distored his views.