National security adviser Richard V. Allen's sale of his consulting firm, which provides him with monthly payments, does not constitute a conflict of interest, a White House lawyer said today.

Allen also was not required to state the income from the sale of his consulting company on his Feb. 19, 1981, financial disclosure report, deputy counsel to the president Richard A. Hauser concluded.

In Japan, the interpreter for the Japanese journalists who conducted the now controversial interview with Nancy Reagan last January said that Allen specifically said that he wanted no money for arranging the interview.

According to a statement released by White House officials today, Hauser conducted a new review of Allen's twice-amended report and determined that Allen need only report his income from the sale of Potomac International Corp. on the next required filing date May 15, 1982.

No funds from the sale were exchanged until last February, the statement said in explaining why Allen's income from the sale to former Reagan speechwriter and public relations adviser Peter D. Hannaford was outside the time period covered by Allen's Feb. 19 report.

Allen is receiving installment payments for what he listed as a $100,000 to $250,000 interest in Potomac International at the end of 1980. "Mr. Allen has no continuing financial interest in either Potomac International or the Hannaford Co. Inc.," the statement said.

Although the statement was made available by White House officials, it was not given to reporters on paper with the usual letterhead of the White House office of the press secretary.

It said that Hauser, who in addition to his counsel role, is "alternate designated ethics official for the White House office," conducted the review of Allen's statement and determined that Allen's income did not have to be listed.

Although the Hannaford Co. Inc. is a registered agent for the Taiwan government and for a business group in Guatemala, Hauser determined that its continuing payment to Reagan's national security adviser does not create a conflict of interest.

In an interview with the Yomiuri Shimbun newspaper, interpreter Chizuko Takase said the controversial $1,000 payment made by the magazine Shufo no Tomo was intended to be an honorarium for Nancy Reagan for granting the interview.

"During the course of negotiations with Mr. Allen for the interview, Mr. Allen said, 'I don't want any money as I will do this out of my good will,' " Mrs. Takase said.

Mrs. Takase, whose husband, Professor Tamotsu Takase, is a long-time friend of Allen's, acted as interpreter for the interview with Mrs. Reagan by writer Fuyuko Kamisaka.

The $1,000 payment has led to calls for appointment of a special prosecutor to determine if there was any wrongdoing on Allen's part. The money was discovered in a safe in an office once belonging to Allen.

Mrs. Takase said in the interview: The honorarium "was handed over by the magazine's assistant editor, Miss Keiko Kimoto, after the interview but I don't remember whether it was Mr. Allen or someone else to whom she gave it."

Asked for a comment on a report from Washington that Allen might have received $10,000 from the magazine, not $1,000 since an envelope with a figure of 10,000 written on it was also found in his safe, she said, "What Miss Kimoto gave was a white envelope and I don't know whether any figure was written on it."

"But I'm sure it was $1,000," she said.