Baseball Commissioner Bowie Kuhn said yesterday that National League expansion might be feasible if cities desiring a franchise aggressively pursue one.

"I wouldn't say the prospects are particularly bright right now," Kuhn told The Washington Post, referring to the senior league's opposition to expansion. "Expansion hinges on two cities coming forward with everything in place.

"They would have to have the proper financing, good ownership, a stadium, a lease agreement and be ready to say to the league, 'Here we are, ready to go.'

"When you put the situation in that context, things look better. Right now everything seems to be in a vacuum; the situation is in a vacuum. But it could change."

The American League expanded in 1976 from 12 to 14 teams, but could not have included Washington in that move, even if it had wanted to, because of Baltimore's territorial rights in the league.

A bill that would remove baseball's antitrust exemption and alter terriotorial rights guarantees has been introduced in the House. Kuhn may hear more about it tonight when he attends the annual Congressional Baseball Game between Democrats and Republicans at Alexandria's Four Mile Run Park.

The National League has been under pressure to expand to 14 clubs but has refused to do so. Those NL club owners who are pro-Washington have insisted this city would be part of any expansion tandem.

While an existing NL team could move to Washington, Kuhn said, "I don't think there's any prospect of a move right now. The only (club) in the past that might have moved has been Oakland. But they have a landlord there who has a lease and intends to keept it.

"Although you probably wouldn't have heard me say this a few years ago, (the lease) is good for baseball . . . it assures stability."

Oilman Marvin Davis tried to buy the a's two years ago for Denver, but his efforts were thwarted, in part, by the A's lease with the Oalkland Coliseum. He remains interested in buying a club, and some NL owners look favorably upon a Denver franchise.

Other cities known to want a baseball franchise are Syracuse, New Orleans and Miami.

With the Baltimore Orioles leading in the AL East Division and drawing record crowds, anymove or shared-franchise plan that had once been entertained is on the back burner, at least until after next season. The Orioles recently signed a new lease committing them to play in Baltimore through 1980.

Kuhn said developments during the past few months make it difficult to assess Washington's immediate future in baseball.

"I really don't know how to evaluate it right now," he said. "But, of course, my attitude (toward Washington) hasn't changed in the slightest . . . I promise to do my very best."