The Justice Department's decision last week to reject Virginia's plan for redistricting its state Senate was arrived at in a routine manner and should not be viewed as an indication of the Reagan administration's preference in the area of civil rights, Deputy Attorney General Edward C. Schmults said yesterday.

"I don't know if it's fair to call any of these cases routine," Schmults said when queried by a reporter, "but it was handled as a matter of course. I don't think this signals anything."

The Justice Department acted under provisions of the 1965 Voting Rights Act, which requires federal approval of districting plans in nine states, most of them in the South. That law is unpopular with conservatives, particularly in Virgina, which voted for Reagan last November and has a Republican governor. The law is to expire next year and many Virginia politicians have told Congress that, because of progress the state has shown in complying with civil rights laws, it should not be extended.

Officials in the Justice Department's civil rights division turned down the Virginia Senate redistricting plan, the first the division has considered since the 1980 census, on the grounds that it discriminates against blacks in Norfolk, the state's largest city.

Schmults, the number-two federal law enforcement official, said the question of the law's expiration was not a consideration in the Justice Department's decision.

"The law is on the books and we're here to enforce it," he said. Although President Reagan has voiced a strong preference for states' rights, Schmults, said White House officials were advised of the decision only after it had already been reached, and then only as a matter of courtesy, "because I expected the papers would pick up on it."

"None of these are really relevant concerns," Shmults said.

In examining the Virginia plan, civil rights officials found that it discriminated against Norfolk's blacks, who comprise 35 percent of the population, by separating them into two senatorial jurisdictions. The plan would have replaced the current one, under which Norfold voters elected three state senators at large.

Although Norfolk Del. William Robinson Jr., a black, called the new plan "the lesser of two evils," the Justice Department found that the choice of boundaries was made "with the full awareness and expectation that it would fragment the black electorate."

James P. Turner, acting assistant U.S. attorney general in charge of the civil rights division, wrote that the state "has presented no plausible, nonracial justification" for the new lines.

Both candidates for the Virginia governor's office, Democratic Lt. Gov. Charles S. Robb and Republican Attorney Gen. J. Marshall Coleman, have said that Virginia's record of compliance with civil rights standards should exempt the state from further federal scrutiny.

Reached yesterday at a meeting of the state Democratic Party central committee in Richmond, Robb said he planned to meet with members of the legislature next week and the Justice Department decision "will be high on our agenda."

"I was concerned prior to the decision that Virginia seemed not to have any [civil rights] violations, and it seemed unfair that the state should not be exempt from the preclearance provision" of the Voting Rights Act, Robb said. "I'm sure than an action has been taken that is authorized and that it would stimulate additional discussion."

Coleman, who was compaigning yesterday, could not be reached for comment. His press aide, David Blee, said: "It is law right now, and the fact that we favor its expiration is really irrelevent. What we want is what's best for Virginia."

Indicative of the differences between downstate views and those held in the Northern Virginia suburbs, 10th District Republican Rep. Frank Wolf of McLean said yesterday that he supports an extension of the Voting Rights Act, but would like to see a provision "for certain areas of a state to be exempt."

Deputy Attorney General Schmultz, as well as various Virginia legislators, expressed hope that the redistricting dispute could be settled without going to court. Elections to the 40-member state Senate are not scheduled until 1983 "and there's time to work that out with us," Schmults said.

Virginia's plan for redistricting its 100-member House of Delegates, for which elections are to be held this fall, also is being considered by Justice. That plan, too, is being contested by civil rights groups. A ruling is due Aug. 16.