In a decision likely to inhibit the spread of cable television to urban areas, the Supreme Court held yesterday that states cannot bar landlords from charging fees to cable television companies that install equipment on their buildings.

The 6-to-3 decision rejected New York's practice of allowing cable companies to install cable equipment on apartment rooftops for a nominal fee. A state law prohibits landlords from charging more than a "reasonable fee" to cable operators, and a state commission found that a one-time, $1 payment was "reasonable."

Yesterday's decision, by Justice Thurgood Marshall, held that the "physical intrusion" of cable wires and boxes onto landlords' rooftops constitutes a "taking" of the landlord's property that, under the Constitution, requires "just compensation."

The court's decision ducked the issue of how much compensation cable companies must now pay. Three other states--Connecticut, Florida and Massachusetts--have similar laws, which are designed to prevent landlords from charging exorbitant fees to cable companies that want to serve their tenants or stretch cable wires across their roofs to reach neighboring buildings.

"This will make it more difficult to bring cable television service to people who live in apartment houses," the National Cable Television Association said.

An estimated 24 million subscribers nationwide receive cable television, and half of American homes are expected to subscribe to cable by 1990.

The case, Loretto vs. Teleprompter Manhattan CATV Corp., was a class action brought by a Manhattan apartment owner who complained that the law interfered with her property rights.

Marshall, one of the court's most liberal members, joined Justice William H. Rehnquist, one of its most conservative, in agreeing with that assessment.

"Takings" cases in recent years have attracted unusual coalitions among the justices, with conservatives, who put a premium on private property rights, aligning with liberals, who are staunch defenders of all constitutional protections.

Justice Harry A. Blackmun, writing for the dissenters, called the decision an "archaic judicial response to a modern social problem" that is "potentially dangerous as well as misguided."

Blackmun noted that New York landlords are required by law to provide and pay for mailboxes that occupy more than five times the space occupied by cable connections. "If the state constitutionally can insist that appellant make this sacrifice so that her tenants may receive mail, it is hard to understand why the state may not require her to surrender less space, filled at another's expense, so that those same tenants can receive television signals," Blackmun said.

Justices William J. Brennan, Jr. and Byron R. White joined the dissent.