Senate Majority Leader Robert C. Byrd sternly rebuked President Carter yesterday for "overreacting" to congressional surgery on his energy proposals and said the administration has yet to learn how Congress works.

In a Dutch-uncle lecture embodying his strongest criticism yet of the new Democratic President and his energy program, the Senate Democratic leader suggested to reporters that Carter "cool it just a bit at this stage and let the process work."

The West Virginian said he believed from the start that administration's energy program had "obvious flaws," although he hesitated to speak out until he analyzed it fully.

So he was not surprised, he said, when the House Ways and Means Committee on Thursday rejected two key elements of the plan: standby authority for a tax on gasoline and rebates on purchases of fuel-efficient cars.

They were ill-conceived and likely to be ineffective in conserving energy, said Byrd.

It was rejection of these two proposals coupled with a House Commerce subcommittee's vote to decontrol the price of new natural gas, that prompted Carter to charge Friday that the House panels had caved in to auto and oil lobbies at the expense of consumers.

Responding to questions at his regular Saturday morning press briefing at the Capitol. Byrd said the reference to industry lobbying was "unfair."

The most powerful, active lobby in town is not the corporations, uniors or other nongovernmental groups but the executive branch, said Byrd.

All all too often, he said, when the White House fails in lobbying efforts, "Congress is made the butt of unfair criticism."

Byrd said he was not overly concerned about prospects for strong energy legislation because the House committee action is "only the first pitch in an energy ballgame that may go 10 innings or more."

He said the administration plan was a "building bloack" rather than the "alpha and omega" of an energy solution, and indicated it may be changed even more - "hopefully strengthened," said Byrd. As it stands now, it doesn't even meet the President's own objectives, he added.

Byrd termed Carter's criticism of Gongress a "mistake" and added:

"I think it was an overreaction and that it was uncalled for at this point and does not reflect an awareness of how the legislative process works."

Suggesting that the White House would be wise to exercise more patience, he said that "before negativism should reign, we ought to wait and see what product evolves from the lengthy legislative process."

Byrd, who has frequently urged the administration to consult more fully with Congress and seek its advice in advance, said the "situation has improved" but there is still "a problem of no little significance."

He cited administration consultations with Congress on treaty negotiations for the Panama Canal and on strategic arms limitations between the United States and the Soviet Union as examples of improved cooperation. Another example, he said, was a compromise leading to Senate passage Friday of the administration-backed clear air bill.

Defending Congress' record on energy, Byrd said it has already approved several energy-related measures, including creation of a Department of Energy, strip mining controls and the clean air bill.

He said the Senate, which is contemplating holding hearings as early as 7 a.m. to handle administration and other proposals, is clearing its decks for energy legislation and on Monday will consider a $2.4 billion authorization for energy research.

On the specifics of Carter's energy program, Byrd said he thought the rebate for high-mileage cars was "bad from the start" because the revenues should be used for fuel-conservation measures rather than given back to car purchasers. He said he considered the standby gasoline tax "a very nebulous, vague and inefficient way to bring about conservation." He did not discuss other aspects of the program.