Virginia Gov. Charles S. Robb and one of his top transportation aides warned today that the politically popular effort to reduce car-pool restrictions on Rte. I-66 could be vetoed by either Metro or the Metropolitan Washington Council of Governments.

The governor and deputy state transportation secretary William Landslidle said both agencies have told Virginia officials they are firmly opposed to any immediate change in the rules that restrict rush-hour traffic on the eight-month-old section of the highway inside the Capital Beltway to cars with four riders.

For that reason and on the advice of transportation planners, Robb said he does not plan to press for any change in the rule until several months after a section of highway linking the interstate with the Dulles Airport Access Road opens, probably this fall. "The professionals tell us this is not the time to seek change," Robb said.

Although neither official directly attacked the two Northern Virginia members of Congress and local officials who have been pressing for a change in the rule, Robb made clear he was frustrated that much of the debate has seemed to focus on the seeming resistance of state officials to the change. "Resent may be the wrong word to use," he said at one point, noting that the state was "only one of four players" who must approve any car-pool changes on I-66.

Under the terms drafted during former president Ford's administration, Virginia, the Federal Highway Administration, COG and the Metro transit system all must approve any changes in the I-66 car-pool rules.

The rules for Shirley Highway are set by the state, but District of Columbia officials have indicated they are opposed to any changes that would place more rush-hour traffic on either the Theodore Roosevelt or 14th Street bridges, the officials said.

Robb said that he didn't view that opposition as fixed and said he would go directly to D.C. Mayor Marion Barry to press the state's position if a study calls for changes in the restrictions. But at the moment, Robb said he didn't have any statistics that would support a change in the I-66 car-pool rules. More likely, he said, was an easing of the Shirley Highway express lane rules in the hours immediately before and after the current peak periods.

His comments came during a wide-ranging, 2 1/2-hour luncheon with Northern Virginia newspaper editors at the Executive Mansion. During that session Robb also appealed to officials in the Washington suburbs to allow the state to try another controversial traffic measure--its $22 million computerized traffic control system on Shirley Highway.

The system, which will use 19 traffic lights to control access to the highway, should cut overall commuting time on the highway by 25 percent during the rush hour and will cut accidents by 20 percent, the officials said. Alexandria and Fairfax County have threatened to sue the state to block activation of the lights, which the jurisdictions charge will favor commuters from the outer suburbs at the expense of those from the close-in communities.

"I had some reservations about it, too, until I looked at the consultant's report on the system," Robb said. "If it doesn't work or live up to our expectations . . . regardless of what it costs, then we won't use it."

Landslidle said the maximum delay any motorist will face will be a 2.2 minute wait at one of the on-ramps, but he insisted that the flow of traffic into and out of Washington will improve with the system.

To ease the car-pool restrictions on the two Northern Virginia highways "could be a very popular move in the short run" the governor said. But if the easing only produces more congestion the approving official will "be cussed by future generations."

Robb, who has been pressed by local officials to send more state highway funds to Fairfax County, said he was sympathetic. After all, he said, he plans to return to his McLean home in two-and-a-half years and "I'm going to be right up there in all those traffic jams."