A top official in Ronald Reagan's transition team yesterday appeared to dash the hopes of Fairfax County's top Republican that the new administration would quash a major civil rights lawsuit against the suburban country.

"That's not the way you approach any litigation," said Loren Smith, who is overseeing the GOP takeover at the Justice Department. He indicated that the new administration is not about to succomb to political pressure and drop a suit that has infuriated Fairfax Board Chairman John F. Herrity, the county's top officeholder.

Herrity, who had accused the Carter White House of bringing the suit in an effort to embarrass his jurisdiction, has been predicting that the Reagan administration would be willing to quickly end the dispute.

"I suspect I'll be able to talk to some of the top people in the [Reagan] administration about this," Herrity said confidently yesterday. "I've worked with a lot of them before."

But spokesmen for the Reagan Transistion team later offered little hope that Herrity would be successful in his efforts to torpedo the employment discrimination suit, currently pending before the Supreme Court.

The suit, charging that Fairfax County has discriminated against women and blacks in its employment practices, has been a thorn in Herrity's side ever since it was filed two years ago.

Herrity maintained that it was a "political mumbo-jumbo suit," the product of a Democratic administration bent on discrediting his Republican government.

"We're trying our best to treat people fairly in this county and we have an affirmative action plan, and now we're being asked to spend a whole lot of money defending it," Herrity fumed yesterday. "I just don't think it's fair."

Justice Department investigators have maintained, however, that Fairfax over a period of years clustered blacks and women in low-paying, less desirable jobs. The county was also criticized for failing to actively recruit women and blacks for its 5,000-person work force, and for inadequate storage of job application records.

A federal appeals court recently sided with the department, overturning a lower court ruling favoring Fairfax and directing a district court judge in Alexandria to reopen the case.

According to records cited by the appeals court, only 7.5 percent of county workers were blacks and only 26 percent were women at the time the suit was filed, as compared with a Washington-area work force that was 24 percent black and 40 percent female in 1970.

Smith who served as legal counsel for the reagan campaign, said he has no idea whom the president-elect will choose as the next attorney general, but said such a choice would have no bearing whatsoever on the Fairfax suit. He also said that he doubted Herrity could use his political influence to end the suit.

". . . I don't think going to the president and saying 'Stop this action' is really the right way to go about it," Smith said.

"Whenever you're considering a specific legal action, you have to be particularly sensitive to the fact that you're dealing with the courts an you're dealing with the law and you have to pay attention to what the law says," Smith said. "If you don't like a particular lawsuit, what you really have to do is work to get the law changed."

Herrity, who could not be reached for additional comment after Smith's statement, had not been specific about how he intended to apply pressure on the GOP administration to end the lawsuit.

In 1979, Fairfax officials had been ecstatic with a ruling by U.S. District Judge Albert V. Bryan Jr., who held that the county engaged in some limited discriminatory practices in the past, but said santions were unnecessary because the county had made significant progress in correcting the situation.