Worried that Congress may not pass an energy bill this year, the National Governors' Association decided yesterday to dispatch a delegation to Washington tomorrow for "an urgent conference" with President Carter and congressional leaders.

The delegation of about 15 governors will be led by Julian M. Carroll of Kentucky, the association's new chairman, who said, "It could be catastrophic for the nation if Congress fails to pass legislation that increases energy production. If that happens, the nation could face substantial unemployment, extended inflation and continued devaluation of the dollar."

The governors, ending their 70th annual convention here yesterday, passed a resolution saying they were "greatly concerned about the serious implications for the nation if Congress fails to reach consensous before the end of this session,"

Senate and House conferees have agreed on a bill that includes phased deregulation of new natural gas, and the measure is expected to come to a vote after Congress returns from its Labor Day recess. In the Senate a filibuster is threatened and 18 senators have signed a letter calling on the conferees to work some more on the bill.

Carroll said thegoverners had planned to consult the president next week, but he noted that Carter will be conferring then at Camp David with Israeli Prime Minister Menachem Begin and Egyptian President Anwar Sadat on the Middle East.

"We decided it would be dangerous to delay further because Congress could consider the bill as early as next week," Carroll said. "We don't know whether any congressional leaders will be in town Thursday, but we'll try to see whomever is there."

The association, which had earlier endorsed natural gas deregulation, said yesterday the legislation should include "effective conservation and production components."

During their three-day meeting here, individual governors criticized Congress for the energy impasse, and William G. Milliken of Michigan, a Republican, called the lack of action "unconscionable."

The association also pressed for a balanced federal budget by fiscal 1981, expressing "great concern" that since World War II federal spending has risen to a 22 percent share of the gross national product.

Democratic Gov. James B Hunt Jr. of North Carolina, who proposed the fiscal restraint resolution, noted that Carter had campaigned on a pledge to balanced the budget by Sept. 30, 1981, and added, "I think the problem is in Congress. They're voting every day to spend more money."

Gov. David Pryor of Arkansas, also a Democrat, said, "For the life of me I do not feel that Congress has truly gotten the message of what Proposition 13 is all about." That measure, approved by California voters in June, drastically cut property taxes and limited the state's ability to raise new taxes.

Florid's Reubin Askew, a Democrat who is retiring this year, told the association, "This organization has less than a credible record in showing the administration where it could cut. Almost all our resolutions call for more spending.

In approving the balanced-budget resolution, the governors declined to endorse a stronger measure proposed by New Hampshire's conservative Gov. Meldrim Thomson Jr. that would have urged a constitutional limit on state and federal spending.

The association also urged the federal government to reimburse states and localities for the full cost of implementing new congressional and executive programs.

Governors and mayors have long complained that many new federal programs impose additional costs on them. For example, they cite a requirement that new buildings for recipients of federal funds must have ramps for the handicapped, and they say the federal government should pay for them.