Montgomery County high school principals, under fire from county police and politicans, said yesterday that they had devoted only limited time and energy to finding students "smoking dope in the parking lot" for the same reason that police did not concentrate on catching marijuana smokers until the recent crackdown: They have bigger problems to attack.

"Our main job is education, not law enforcement," said Joseph Villani, assistant to the deputy superintendent. "If you want to work on projects for the gifted and the handicapped, evaluate teachers and talk to students, you cannot spend you whole life in the parking lot looking out for kids who are using marijuana."

Police have arrested only one high school student on drug charges this week, but officers denied that their crackdown against student drug users has ended. For the last two weeks police have kept high schools under suveillance and arrested 106 students on charges of possession of marijuana.

Several political candidates have praised police for the arrests and have criticized school officials for not curbing marijuana use among students.

"The bottom line is that schools have not been as concerned with this problem as I think they might have been," said Richmond (Max) Keeney, Republican candidate for Montgomery County executive. And several candidates for school board also criticized school administrators for not curbing marijuana use. Independent candidate Barry M. Klein said he was dismayed at "the failure of the present school administration to enforce the drug ban."

Eleanor Zappone, another school board candidate, criticized principals who have "more lenient or accepting attitudes toward marijuana smoking." She would not name specific principals, but said she thinks such attitudes occur in affluent areas, such as Bethesda and Chevy Chase, where she thinks parents are "less strict with children."

Police Chief Robert J. diGrazia also has criticized principals for not stopping marijuana use among students. At a closed-door meeting with principals and School Superintendent Charles Bernards on Monday, diGrazia said that one of the key program has been that school monitors - school employes who make sure that students go to class and do not use drugs - have been "too much buddy-buddy with students." In some cases, he said, school monitors have not reported students using marijuana to school principals. He told principals they should hire better qualified personnel for the job.

Under Maryland law and school board policy, teachers, administrators and school monitors must notify the principal when they see students using drugs. The principal must notify police, who arrest the student.

Principals said that they have complied with that law. Whenever they see a student using drugs, or whenever a case is reported to them, they call police. But they also say they cannot be expected to spend lots of time looking for students using marijuana.

"I supervise seven departments and 50 teachers," said Charles Rideout, assistant principal at Walter Johnson High School in Bethesda. "I have to organize and run field trips, develop master schedules of classes, and make sure that students get the best instruction there is. I don't have time to be a head-hunter in the parking lot."

Other principals made similar statements. One of them, Joseph Byrnes, assistant principal at Springbrook High School in Silver Spring, said his first priority is "the instructional program." His second, he said, is showing an interest in students' successes and problems. "Sometimes, a problem that a kid tells your about is more important than anything else," he said. "There may be a girlfriend-boyfriend thing where the kid's threatens suicide. You have to give the kids support."

One school board candidate Nancy Weicking, agreed with Byrnes' approach. "Principals are working on the causes of drug abuse rather than taking police action on it," she said. "They try to show kids that they are caring adults. They have to cut down on the large-school feeling that kids get."