FBI Director William H. Webster personally called White House national security adviser Richard V. Allen earlier this month and discussed with him the FBI investigation of the $1,000 in cash found in a safe Allen used, government officials said yesterday.

Precisely why he called and what they said remained unclear last night.

Presidential counselor Edwin Meese III, in an appearance on television, played down the call, suggesting it was routine. Asked on "Face the Nation" (CBS, WDVM) if the contact was proper, Meese said: "Well, as far as Mr. Allen is concerned it was proper for him Webster to talk to him, they were interviewing him as part of the investigation."

Another official, who asked not to be identified, said Webster had placed the call to tell Allen that Allen's version of the $1,000 incident had been confirmed by other participants.

Roger S. Young, a spokesman for Webster, said last night that the director could not respond because a Justice Department restriction on public comment "has not been lifted."

One issue throughout the Allen affair has been whether the investigation could be left to the FBI or should be turned over to a special prosecutor. Justice Department officials acknowledged yesterday that Webster's call to Allen raised the question of whether the FBI conducted its inquiry at arms' length.

The investigation began when an envelope containing $1,000 was discovered in mid-September. Allen has said he intercepted the cash, which was meant for Nancy Reagan as a thank-you fee for an interview she gave to a Japanese women's magazine. He had a secretary put in the safe, intending to turn it over to the treasury, but both of them forgot about it, he said.

On the strength of the FBI's initial investigation, Justice prosecutors recommended early last week that the case be closed without a special prosecutor. But FBI agents were ordered back into the field later after senior Justice officials decided more people needed to be questioned.

One source said yesterday that the figure $10,000 was written on the envelope containing the cash, and that the same figure was written on what appeared to be a "receipt" that also was found in the safe.

Sources have said that those persons interviewed backed Allen's story that the envelope contained $1,000 and that it was not intended for him, but the references to the $10,000 are still unexplained.

And the special prosecutor provisions of the Ethics in Government Act are so easily triggered that unless Attorney General William French Smith can certify the allegation is "so unsubstantiated" that no further investigation is necessary, he might have to ask a special court to appoint one anyway, officials conceded.

Meese said yesterday that there are no plans to oust Allen from his post. But he appeared to leave the door open for action against him should Smith determine that a special prosecutor should be named.

"I don't see any plans at the present time for Mr. Allen to leave the White House," Meese said. Asked again later in the telecast whether Allen might be fired, Meese said: "I think that until and unless there's some adverse information that comes to light, I think the situation will remain as it is."

He said that the final Justice report would "either totally clarify and absolve the individuals involved, or should it be otherwise then appropriate action will be taken." He said "that will be the test that the people will be looking at."

Meese also confirmed he, too, had talked to Webster about the investigation. When White House communications director David Gergen first announced that Meese had talked with the FBI about the investigation Nov. 6, he left the impression that Meese initiated the conversation.

Meese said yesterday that Webster called him. Meese stressed that the conversation was proper because he had been the White House official who first turned information about the cash over to the FBI. He is also Allen's boss.

He said "after a certain portion of the investigation had been completed, the FBI came back to me to give me information as the senior White House official as to whether any administrative action should be taken against Allen pending the outcome of the total inquiry."

Investigators looked into the possibility that the envelope once contained $10,000 and found no substantiation, sources said. The Japanese interviewer Fuyuko Kamisaka, who first disclosed the payment and later revealed that a lacquer box had been given to Mrs. Reagan and two Seiko watches had been given to Allen, has insisted that the amount was $1,000. She has said Allen was given ten $100 bills.