Moscow — Some Western diplomats here are worried that the furor over the Soviet boycott of the Los Angeles Olympics is -overshad-owing important developments regarding Andrei Sakharov, the dissident Soviet physicist.
Dr. Sakharov has reportedly begun a hunger strike to protest new restrictions on his wife, Yelena Bonner, who is seeking to go to the West for medical treatment.
Last week the official Soviet press agency Tass said that Sakharov and Mrs. Bonner had plotted with officials at the United States Embassy here to start an ''anti-Soviet campaign.''
Some diplomats cite similarities between the Sakharov plight and the Olympic controversy. What is at stake in both cases, they say, is the right to criticize publicly without hindrance from governments.
At least one Western diplomat here speculates that Moscow's boycott announcement may have been timed to draw attention away from the Sakharov matter.
After all, the diplomat notes, the Soviet decision was not required by Olympic officials until June 2. And Soviet officials had been suggesting the decision would not be made until late May.
''Why,'' the diplomat asks, ''was the decision announced on May 8 instead of June 2?''
One possible answer: It was timed to coincide with the beginning of the run that eventually will deliver the Olympic flame to Los Angeles.
If speculation that the Soviets wanted to draw attention away from the Sakharovs is correct, it could help explain why the Soviets seem to be sending out contradictory signals on the firmness of their resolve to boycott. But such an explanation is highly unlikely, other observers here say.
Nevertheless, they argue that the two situations clearly point out the fundamental point of divergence between the American and the Soviet systems: the basic notion of what constitutes freedom.
Since the US Constitution guarantees freedom of speech and assembly, US officials have repeatedly told their Soviet counterparts that they could not prevent protest groups in Los Angeles from criticizing Soviet participation in the 1984 Olympics - or even from encouraging East-bloc athletes to defect.
The Soviets say it is the actions of these groups that have forced them to stay away from Los Angeles. That could, of course, simply be a verbal cover used to disguise other possible motives - revenge for the US boycott of the 1980 Moscow Olympics, for example, or a desire to torpedo President Reagan's reelection campaign by pointing up the abysmal state of US-Soviet relations.
Some diplomats suggest the Soviet pique over the US refusal to curb the protesters is genuine, but only because Moscow fears the groups might be successful in spurring defections.
The Soviet government, after all, would simply not countenance such protests in its own country. And it most assuredly does not want Soviet citizens emigrating to the West. The case of the Sakharovs, some Western diplomats say, offers a vivid example of both points.
Freedom of speech is also guaranteed in the Soviet Constitution - as long as it is ''in accordance with the interest of the people and in order to strengthen and develop the socialist system.'' In fact, it is a largely meaningless right, tightly circumscribed by Soviet authorities and by a bevy of laws that provide heavy penalties for such offenses as ''anti-Soviet slander.''
Such constitutional guarantees certainly did not prevent authorities in 1980 from exiling Andrei Sakharov to Gorky, a city some 250 miles from Moscow and off-limits to foreigners. He and his wife have repeatedly been refused permission to travel to the West. Mrs. Bonner has not been seen in Moscow since the government made the charges. Western diplomats here speculate she has been sent into internal exile.
The suggestion that the boycott announcement was timed to overshadow news about Sakharov could vastly overstate his importance to the Soviet authorities. Nevertheless, almost as soon as the boycott was announced, Soviet officials began to suggest it was not irreversible.
Georgi Arbatov, the Kremlin's top expert on the United States, told an American television audience that he was hopeful that assurances would be received from the US government ''because I'm sure Soviet athletes . . . would like to compete with Americans.''
But, he said, Moscow needs assurances that its athletes would be protected not only from physical harm but also from ''attempts to kidnap you or to seduce you to leave your country.''
In Sydney, Australia, the head of the USSR's Olympic ice skating team also hinted that the decision could be changed on receipt of ''assurances'' from the US.
In yet another peculiar footnote to the controversy, the Soviets have confirmed that they will send a basketball team to France to participate in a pre-Olympic qualifying tournament. The confirmation, in the form of a telex, was apparently sent out after the announcement that the Soviets would not participate in the Olympics.
''That does not necessarily mean that they have changed their minds,'' the head of the French Olympics Committee, Nelson Paillou, told Reuters, ''but as the point of the tournaments is to qualify for Los Angeles, it could well mean that they don't consider their decision as irrevocable.''