President Carter late yesterday abruptly canceled tonight's scheduled speech to the nation, which White House officials had billed as his most important address on energy since his "oral equivalent of war" speech two years ago.

Press secretary Jody Powell, announcing the cancellation in a telephone hookup with reporters, gave no explanation for the change in plans.

"The President has asked me to announce that the speech originally scheduled for Thursday night has been canceled," Powell said. "I have nothing further to say than that." However, there were reports that Carter was apparently dissatsified with the draft of the speech.

No new date was set for the speech, and Powell said it was not known when the president would return from his Camp David mountaintop retreat. He also declined to say whether Carter would made his planned trip to the National Governors' Conference in Louisville, Ky., this weekend.

Carter reported decided on Monday afternoon to make a major address on the energy situation, after returning from the Far East. White House officials said the president felt the need to act rapidly, to seize on the frustrations of a public caught in long gasoline lines and the anxieties caused by the most recent price increase by the oil-producing cartel.

A senior White House Official said Carter decided to cancel the speech sometime yesterday, informing Vice President Mondale and presidential aides Gerald Rafshoon and Hamilton Jordan through a telephone conference hookup. The president apparently did not elaborate on his reasons.

White House sources had said that Carter, projecting the image of a hurried president rushing back to grapple with the emergy crisis, wanted to use the occasion to bolster his image as a strong leader and build support for some of his faltering energy programs.

Those programs include a standby gasoline rationing plan, which the House rejected overwhelming, and a new tax on the "windfall profits" of oil companies, which the House has sharply weakened.

Before Carter decided to cancel his speech, Powell told reporters that the address would sketch the broad outlines of administration policy, whilte the specifies would be forthcoming sometime next week.

White House officials also suggested that Carter might use the occasion to advocate an extensive synthetic fuel indistry, and possibly the creation of a "Synthetic Fuel Development Authority" to reduce the reliance on imported foreign oil.

Carter was also said to be considering a new tax on large "gas-guzzling" automobiles, and a relaxation of antipollution standards to allow the use of "dirtier" fuels like coal.

But some Carter aides were reportedly uneasy about the hastily scheduled speech, expressing concern that the president felt the need to give a major energy address without having anything specific to say.