The Reagan administration, in a statement personally approved by the president, today sided with the declaration of Jordan's King Hussein that his nation is not a Palestinian state.

Hussein was responding to Israeli Defense Minister Ariel Sharon, who said repeatedly during a U.S. visit that ended today that Jordan is a Palestinian state and should become the permanent homeland of the Palestinian people.

"The Reagan administration, like its predecessors, is committed to the territorial integrity and sovereignty of Jordan and our support for its enduring character," White House deputy press secretary Larry Speakes said today in reiterating the U.S. position on the issue. "We do not agree that Jordan is a Palestinian state."

Speakes read the statement at the daily White House briefing, held in a Santa Barbara hotel while President Reagan vacations at his nearby ranch in the Santa Ynez Mountains. Reagan discussed the statement this morning by telephone with national security adviser William P. Clark.

The statement was similar to one issued last Thursday and Friday by the State Department, as the White House sought to reemphasize the point in the wake of statements by Hussein and Sharon in television interviews Sunday.

Hussein said on ABC-TV's "This Week with David Brinkley" that Jordan associated itself with Palestinian hopes and aspirations but added that Jordan had given the Palestinians only a temporary home "awaiting resolution of their problem on their legitimate soil."

In a restatement of long-held positions, Hussein contended that a Palestinian homeland must include the Israeli-held West Bank of the Jordan River as well as the Gaza Strip and East Jerusalem. Sharon, who rejected that contention, was interviewed on the same program and on CBS-TV's "Face the Nation."

Explaining the White House statement today, an administration official said the U.S. government wanted to make clear its support for Hussein's position while Sharon was still in this country. Sharon flew back to Israel this afternoon after a five-day U.S. visit.

The official said that the administration does not want to pressure Jordan, where more than half of the population is Palestinian, to assume the sole responsibility for providing a homeland for Palestinians on the West Bank.

Speakes also questioned the accuracy of Israeli Prime Minister Menachem Begin's statement in an interview published in The New York Times Sunday. Begin quoted Reagan as describing the recent Israeli bombing of Beirut as a "holocaust," a term usually reserved to describe the Nazi extermination of Jews during World War II.

In the interview, Begin said he was "deeply hurt" that Reagan had used the term during an Aug. 12 telephone call in which the president complained that the bombings were jeopardizing prospects for peace in Lebanon.

Speakes, while questioning the accuracy of Begin's recollection, said he had "not been able to track that down" and did not know the precise word the president had used to describe the Israeli attack.

On domestic matters, Speakes said the $98.3 billion tax bill passed this month by Congress would not reach the traveling White House until later this week and might not be signed until Reagan's scheduled return to Washington Sept. 7.

He declined to predict victory for the administration in sustaining the veto of the $14.2 billion supplemental appropriation bill that Reagan rejected Saturday on grounds that it contained "wasteful and unnecessary spending."

Privately, administration officials believe they can sustain the veto, but to keep the military paid and some smaller federal agencies functioning normally through Sept. 30, they would also have to win congressional agreement on a new supplemental acceptable to Reagan.

They are concerned, however, that it may be difficult to persuade Congress to include the $350 million Caribbean Basin Initiative in a future supplemental bill as Reagan requested in his veto message. "We may have scuttled our own foreign policy initiative," one official said.

Reagan and his wife spent the day at their ranch in the company of William and Elizabeth Wilson, two longtime friends. Wilson, a wealthy investment counselor who is the administration's emissary to the Vatican, recommended to Reagan in 1974 that he buy the ranch property 29 miles northwest of here.

Senior staff members also used the opportunity to take time off. Today was one of the few times under the administration when the senior staff trio of James A. Baker III, Edwin Meese III and Michael K. Deaver was away.

Baker and Meese spent last week here, and Deaver is scheduled to arrive Tuesday for the duration of Reagan's vacation at the ranch.