The Justice Department, which said Monday it may ask the courts to dismantle court-ordered busing plans in several major cities, already has received requests to intervene in desegregation cases in Boston and St. Louis.

William Bradford Reynolds, head of the Civil Rights Division, said the department is looking into the busing situation in several cities. If a specific request is made by local school officials, Reynolds said, the department would consider intervening to ask the court to throw out busing plans that are not working.

John Wilson, a spokesman for the division, said yesterday that no decision has been made yet on going forward in any specific case, and he does not expect a decision soon.

Wilson would not say which cities are being looked at by Justice, but department sources have said the change in policy could lead to reopening cases in Boston, St. Louis, Cleveland, Memphis, Detroit and Denver.

In his news conference last night, President Reagan said the Justice Department announcement on busing is "no change in policy."

"What the . . . department has said is in those areas where there has been court-ordered busing, if the community is seeking to have that changed in court, on a case-by-case basis, . . . the Justice Department would join the community into going into court on that case."

The president said there has been "so much court ordering" of busing "and some of it has seemed to be a violation of the rights of the community and the rights of local school boards and so forth."

He also said that "the people that were supposed to benefit from the busing are the ones who are bringing the cases. The black community is the one that is protesting."

The Civil Rights Division's Wilson said that there have been requests from Boston from both blacks and whites affected by the case. Requests in the St. Louis case have come from both Rep. Richard A. Gephardt (D-Mo.) and Missouri Attorney General John D. Ashcroft.

Robert Crider, president of the Denver school board, said he was confused by the change.

"I'm not sure what their plans are . . . . We've just gotten the city settled down again after the latest busing order ," he said. "They've created enough controversy with what they've said. I think they have a responsibility to come forward with some guidelines."

Roger Lulow, acting superintendent of the Cleveland public schools where court-ordered busing began last year, also expressed some caution about asking the department to intervene. "Some parts of the community think we should jump on the Justice Department bandwagon -- others disagree . . . . If you get back in, you resurrect all the hostility that hopefully the community has put aside."

But Randy Sissel, a spokesman for the Missouri attorney general, said Ashcroft was very encouraged by the decision and planned to contact Justice again soon.

The Justice Department has already moved in a case in Baton Rouge, La. Last month a federal appeals court was asked to allow reconsideration of a desegregation plan there on the grounds that white students were fleeing the public school system.

Among school districts involved in court-ordered busing, every one contacted complained of a drop in enrollment, generally in white students, following implementation of busing plans.

In Denver, since busing began in 1969, enrollment has fallen from 96,000 to about 60,000 and the percentage of white students from 70 percent to 39 percent.

Anthony Sestric, an attorney representing a white parents group in St. Louis, said both black and white students have left the school system. The number went from 79,000 in 1979, the year the busing plan was first discussed, to 49,000 this year.

Boston has experienced white flight since the first phase of busing began in 1974. Whites then accounted for 70 percent of enrollment with blacks and other minorities making up 30 percent. Today, those figures have been reversed.

Recently a black parents group petitioned the court to allow students to go to the school of their choice, complaining that because of the rigid racial quota system imposed by the court in the city's magnet school, seats are being left empty while black students stay on long waiting lists.