Democrat Charles S. Robb lashed out at Republican Gov. John N. Dalton for the first time in the campaign for Virginia's governorship today, saying Dalton had demeaned himself and his office by making a television and radio advertisement attacking Robb's integrity.

Robb, who in the past has praised Dalton's performance as governor to the dismay of fellow Democrats, said the governor had overstepped the bounds of ethical campaigning in the ads. Dalton accuses Robb in the ads of making "absolutely false charges" about Republican gubernatorial candidate J. Marshall Coleman in Robb's ads.

"When someone who's currently serving as governor comes on and uses that office in a way that singles out and attacks the personal integrity of someone who has at the least been overly fair to him, it seems to me to have been kind of a low blow," said Robb in an interview.

"He's lowering himself to the level of the campaign he's supporting and I don't think that as governor he ought to do that," added Robb.

Dalton said through a spokesman today that "the commercial is not intended as any attack on Chuck Robb's integrity and it's unfortunate if he feels that way." The governor again accused Robb of distorting Coleman's record in his ad campaign, adding "in any political campaign, the candidate must rightfully take responsibility for messages which appear on his behalf; in this case Chuck Robb must take responsibility for that false accusation."

Meanwhile, the Robb campaign unveiled the third in a series of radio ads attacking Coleman's position on campaign issues. The new 60-second spot, which features Fairfax County prosecutor Robert F. Horan, derides the Republican's proposed uniform sentencing law as misleading and "patently nonsense" and contends Coleman "plays with this sentencing question just like a pitchman in a sideshow."

Today's charges were the latest round in an increasingly bitter and personal campaign between Robb, who recent polls indicate is the frontrunner, Coleman and their respective supporters. The charges follow a brief, one-week truce during which Robb announced he had pulled one of his more controversial ads and Coleman had called for a "cease-fire" on negative campaigning.

Robb's statement was triggered by a new 30-second Dalton spot that begins with a deep-voiced narrator announcing "an election alert from Gov. John Dalton." The Republican governor, who appears to be sitting at his desk in the governor's office, praises Coleman who he says "led the fight against marijuana pushers and drug smugglers. I know that, you know that, Mr. Robb knows that -- but false advertising says just the opposite."

Dalton characterizes Robb's ad as "the kind of campaign Virginians don't like. I think Mr. Robb will find that out."

Dalton is referring to an earlier Robb radio spot criticizing Coleman for being quoted in a Richmond newspaper in 1978 as saying "marijuana is no longer a serious problem," a statement Coleman now denies making. The ad concluded that "Chuck Robb knows that drugs are a big problem in Virginia. Marshall Coleman is not so sure."

Robb said his commercial was designed to point out inconsistencies between Coleman's past and present statements. Coleman struck back with an ad that said the Democrat's charge was "enough to make you wonder what Robb's been smoking."

Dalton has campaigned intensely for Coleman and has signed a pair of fund-raising letters that imply the conservative Robb is a Great Society liberal like his late father-in-law, President Lyndon Johnson. But Robb had demurred until his unusually harsh response today.

Robb said that while he expected Dalton "would do everything appropriate as titular head of his party, there are bounds of propriety. If there's any issue on which I feel I'm reasonably unassailable its on personal integrity and to be attacked on that ground is obviously inappropriate and unfair . . . . It's demeaning."

He added that the governor's intense support for Coleman stemmed from the Dalton's desire to be reelected in 1985. Under Virginia law, governors cannot succeed themselves but may serve more than one four-year term.

"I know it's important to have a successor he feels to be beholden to him because of his own ambitions for the future," said Robb. Dalton's press spokesman, Charles J. Davis, refused to comment on this statement.

Coleman spokesman David Blee said Robb's attack was "consistent with the Robb strategy -- what he's done instead of debating the issues is attack the governor personally."