Interior Secretary James G. Watt said yesterday that he did not intend to threaten Israeli Ambassador Moshe Arens when he wrote him last month that American support for Israel might be jeopardized if "liberals of the Jewish community" oppose President Reagan's energy policies.

"There's no threat intended," Watt said. "To have a threat, you have to say we'd do something if they American Jews didn't do something." Watt said the message in this case is, "If you don't support this, the Reagan administration is going to go ahead doing what's right whether you support it or not."

Meanwhile, the White House moved yesterday to dissociate itself further from Watt's letter.

"The main quarrel we have with it is it does not represent administration policy. It is not the president's viewpoint," said deputy press secretary Larry Speakes. Earlier, the White House had issued an official statement disavowing any connection to the June 17 letter and calling its contents "unfortunate."

Watt's explanation came hours before Sen. Daniel Patrick Moynihan (D-N.Y.), one of 12 senators who voted against Watt's confirmation, called on him to resign his Cabinet post "for this bare-knuckled act of bigotry." If Watt does not resign, Moynihan said, "President Reagan should dismiss him immediately."

Rep. Benjamin S. Rosenthal (D-N.Y.) also urged Watt's resignation, calling him a "burden to the president that the president can no longer carry." Rosenthal said he found it "incredible for a Cabinet officer to make a statement like that. It clearly disqualifies him from continuing to serve in his post."

Administration officials indicated that there are no plans to ask Watt to resign over the letter.

In a telephone interview with the Associated Press yesterday, Watt said he was being attacked with "malicious intent."

"Those who have enough integrity to read the letter will understand that it is a good letter because it puts America first," he said.

Asked earlier why the White House would characterize the letter as unfortunate, Watt replied, "It is unfortunate that there would be segments who would intentionally misinterpret the letter."

Watt's letter, whose contents were reported in yesterday's Washington Post, cautioned that "the friends of Israel" should support the Reagan administration's energy policies "if they really are concerned about the future of Israel."

Watt portrayed those policies, including Watt's controversial proposals to speed offshore drilling and coal mining on public lands, as keys to national strength.

"If the liberals of the Jewish community join with the other liberals of this nation to oppose these efforts, they will weaken our ability to be a good friend of Israel," he wrote to Arens. "Your supporters in America need to know these facts."

The letter drew an angry reaction from several Jewish leaders, who denounced Watt for appealing to a foreign ambassador for their support and accused him of making veiled threats.

The uproar was reminiscent of the reaction to Watt's earlier remark that "I don't use the words Democrats and Republicans . . . . It's liberals and Americans." Watt has dismissed the earlier remark as a joke, but continues to characterize those who oppose his policies as "liberals," while calling himself "hard line for America."

Responding to reports of the Arens letter, Rep. Toby Moffett (D-Conn.) sent Reagan a letter asking for an explanation of any links between Israel and domestic energy policy. He called Watt's letter "highly inappropriate and inflammatory."

Watt's explanation of the letter came during a three-hour interview early yesterday on "The Larry King Show," a national call-in radio program of the Mutual Broadcasting System. He said the letter was personal and was not intended to reflect administration policy. Watt also said he believes American Jews "are Americans first."

Watt wrote the letter, he said, because he wanted to commit his views to paper following a social conversation with Arens about energy and other matters at a Bonds for Israel dinner. It was headed: "A Personal Communication."

He said he wants the support of all interest groups, and sought Jewish support in that context. "We need the support of the liberal Jewish community," he said. "We already have the support of the conservative Jewish community . . . . Conservative Jews have supported the president marvelously."

Reaction to the letter varied widely among the listeners, who split about half and half as supporters or opponents of Watt's policies.

A caller from Bangor, Maine, reprovingly asked Watt if he had solicited support from other ethnic groups from other foreign ambassadors. Watt said he had not.

But a fan from St. Petersburg, Fla., called in to say, "As an American Jew I support your statement. There are liberal Jews in this country who forget a strong energy independent United States is the best thing that ever happened to Israel."

Watt said he was not hurt that the White House termed his remarks "unfortunate." He said he told the White House press office to "do whatever they wanted to do. It was my position and I could defend it ably with or without their help."

After that remark, Watt's friend and press secretary, Douglas Baldwin, who sat with Watt in the broadcasting booth throughout the program, flashed his boss a thumbs-up sign and smiled.