Chief Justice Warren E. Burger issued an order yesterday temporarily blocking demonstrators from sleeping in 45 tents they pitched on the Mall and in Lafayette Square to protest what they see as the plight of the District's homeless.

Burger issued his order after Solicitor General Rex E. Lee asked the Supreme Court to delay last week's U.S. Court of Appeals ruling that permitted people to sleep in the park and on the Mall as part of a demonstration supporting the city's street people.

Burger's order specified no time limit, but the full court is expected to consider today whether to extend the stay or lift it.

Mitch Snyder, leader of the Community for Creative Non-Violence (CCNV), the group that yesterday erected 20 tents in the park and 25 on the Mall, said only a few people would keep a vigil at the two tent enclaves until it is clear whether the sleeping protest is legally sanctioned.

"We're not going to flout Burger's ruling," he said. "We're trying to be reasonable." Snyder said that if the Supreme Court continues to block the appellate court ruling, "We will abandon the demonstration."

CCNV has called the collection of Lafayette Square tents "Reaganville" and posted a sign saying it is a demonstration of "Reaganomics at work, population growing daily." The tent city on the Mall is called "Congressional Village, a tribute to inaction and indifference."

At issue in the court case is whether a National Park Service regulation prohibiting sleeping overnight on some federal park grounds violates the protesters' First Amendment rights of freedom of expression.

Lee contended in his Supreme Court brief that allowing protesters to "sleep overnight . . . is not necessary to the exercise of their rights of free speech and assembly."

The American Civil Liberties Union and the Institute for Public Representation, which are representing the CCNV in the case, have contended that sleeping overnight in the park is a form of expression protected by the First Amendment.