Virginia Gov. Charles S. Robb said today he believes the General Assembly has pledged enough state money to Metro to assure continued federal aid for subway construction in the Washington area.

The governor said he could offer "no absolute certainty" that U.S. Transportation Secretary Drew Lewis will agree that Virginia's funding meets the "stable and reliable" criteria that Lewis has demanded before he releases another $1.7 billion in federal construction funds.

"But I think we have made our case," said Robb in his first meeting with reporters since the legislature adjourned Sunday.

Some Fairfax County supervisors have questioned whether Lewis will approve the funding package even though area legislators have hailed it as a major victory for Metro.

The governor revealed today that he wrote Lewis earlier this month, giving a rough outline of what he hoped would be enacted by the legislature. The assembly produced what Robb had sought: a state-wide gasoline tax that provided an additional $28 million for Metro during the next two years.

Robb said Lewis' answer was not conclusive. "We got from him what I believe is as much of a commitment as he could make," said Robb, "He went about as far as he could go. If it is not acceptable ultimately, we will have to consider other courses of action."

Sen. Adelard L. Brault (D-Fairfax), who helped develop the Metro funding package, said again today he is confident that the federal government will accept the state's plan, provided the local governments continue their share of Metro funding. "What Lewis said is that we're moving in the right direction," said Brault of the secretary's telegrammed reply to Robb.

Brault said Lewis' final answer will be available sometime after April 15 when Metro submits its total funding package--including the record $41.7 million in Virginia's 1983-1984 budget--to the federal government for approval.

Fairfax County supervisors yesterday argued that the state's increased contribution to Metro will offset only marginally the burden of local governments in shouldering the system's operating subsidies. After meeting with some of the supervisors today, Brault said he doubted there was any need for clarifying amendments to be added to the state's Metro package.

Robb, obviously pleased with his own lobbying efforts, gave the legislature "high marks" for addressing the critical needs of the state's Highway and Transportation Department and for moving to raise the level of teachers' salaries in Virginia--two priorities he set when he took office two months ago.

"We provided for the essential needs . . . without any major tax increase," said Robb, adding that he didn't have "too much to be disappointed about" as a result of the 60-day session. "The bottom line obviously had to do with money and I think we achieved our goals."

Robb stressed that none of the measures passed by the General Assembly involved an increase in any of the state's general taxes--sales, income or corporate. The bulk of the approximately $400 million in new revenues raised for the biennial budget will come from the 3 percent tax on wholesale gasoline sales; the rest from higher levies on hard liquor, marriage licenses, truck and auto licensing fees and the deferral of corporate tax credits for accelerated depreciation.

Robb said that the legislature stumbled on issues of importance to women and blacks, two groups credited with helping to put him to office. "In the area of symbolism, the results were mixed at best," said Robb, noting the defeat of the Equal Rights Amendment and a state holiday for Martin Luther King.

In particular, Robb said he was "very disappointed" in a House committee's vote to kill a bill denying tax-exempt status to segregated schools. Although he said the issue, touched off by Reagan administration actions, had been misconstrued, he acknowledged that it held "very important symbolism" for Virginia's blacks.

Robb intervened on the last day of the session to try to reverse the vote of the House Finance Committee, but, in spite of assurances from some committee members, the bill was never revived. "I think we made a good-faith effort in a short period of time," said Robb, "I am clearly on the side of those who find totally unacceptable any state or federal incentives for discrimination on racial grounds."

Robb said he had limited his involvement on some issues to preserve his clout for the resolution of the state's fiscal problems. "If I had gotten more involved, I would have severely limited my ability to deal with the General Assembly on other issues."