Anthony P. Puca, twice an unsuccessful candidate for elective office in Montgomery County, said yesterday he plans to run for county executive in the Democratic Party primary in September.

"My only commitment will be to the citizen now," said Puca, a 38-year-old businessman who lives in Gaithersburg. "I'm not concerned about those who may move here 10 years from now."

Puca, who waged an unorthodox and aggressive campaign in a 1982 state Senate primary, announced his intention to run for executive at what he described as a "hastily called" news conference yesterday in the press room of a county government building in Rockville.

Puca, vowing to fight to preserve the "quality of life" in Montgomery, called for limits on new commercial and residential construction, development that he said would reach "almost pornographic" levels in the Rockville-Gaithersburg area.

Puca has no political organization and has yet to file formally for the Democrats' Sept. 9 primary or begin raising money for the race. The primary race already includes two well-financed candidates, state Sen. Sidney Kramer and County Council member David L. Scull, and county recreation director David Robbins.

Albert Ceccone and Edward J. Gannon are competing for the GOP nomination.

Jay S. Bernstein, the head of Montgomery's Democratic Party, dismissed Puca's election chances, calling him "the perennial candidate."

Puca ran for a seat in the House of Delegates in 1978 and, in a vitriolic contest in 1982, tried to unseat state Sen. Laurence Levitan, getting 3,777 votes to Levitan's 4,838.

This year Puca is brushing aside the skeptics in his own party: "This isn't a trial balloon. I wouldn't be sitting here if I weren't confident."