Metro General Manager Richard S. Page warned Washington business leaders yesterday that a wildcat transit strike is possible July 1 over a cost-of-living escalator clause for employes that the transit agency wants to curtail.

Pages's comment to the Federal City Council was the first public speculation from either side about the possibility of work stoppage, which would violate federal law. It was a clear bid by the Metro chief for support from the business community.

Metro's contract with Local 689 of the Amalgamated Transit Union, which expires tonight, provides for quarterly pay increases for 4,800 drivers, mechanics and other employes equal to the rise in the consumer-price index. The provision is unique among public employes in the Washington area. i

The latest payment was at an 18 percent annual rate. But Metro's board, adopting the agency's budget, voted last week to limit any increases to 6 percent for the year. Larger increases would push the system's tax-subsidized operating deficit beyond a budgeted $116 million.

The terms of the expiring contract will continue in effect as the cost-of-living clause and other unresolved issues are decided by binding arbitration.

"Our concern is that . . . the procedure will drag out . . . beyond July 1," Page said, when the next cost-of-living payment would be due under the old contract. If that happens, he said Metro will seek a ruling that the payment need not be made.

If the payment id skipped, Page said, "We could have some wildcat work trouble around July First."

A similar dispute in 1978 precipitated a wildcat strike that halted bus and subway service for eight days.

Charles Boswell, the new president of the union local, deplored Page's statement. He told a reporter the union would insist on the July 1 payment. Without it, he said, his members doubtless would become restive, but he would not speculate about an illegal strike.