Regular marijuana smoking by high school seniors dropped sharply last year, but the use of stimulant drugs--"uppers" such as amphetamines--increased significantly, according to a government-sponsored national survey released yesterday.

The reason for the decline in marijuana use was attributed to increased concern about the health hazards of smoking marijuana and the feeling that young people are less rebellious than they were in the late 1960s and the 1970s.

The reduction in daily marijuana smoking represented the "most substantial, single decline since we first began to see an increase in the 1960s," said Dr. William Pollin, director of the National Institute on Drug Abuse. "It's the first year that we are sure it's real and that it's substantial."

"It leaves no doubt that a real and important downward trend is occurring, rather than any sort of temporary pause in the long-term increase," agrees Dr. Lloyd Johnston, a Michigan researcher who directed the study.

The reduction continues a three-year decline, dropping from a high of 10.7 percent of daily users in 1978 to 10.3 percent in 1979, 9.1 percent in 1980, and 7 percent in 1981. Last year's drop of just over 2 percentage points was greater than the two previous years combined, but one in 14 seniors say they still use marijuana on a near-daily basis.

The researchers said the number of students using marijuana at any level also appears to be declining, though less dramatically than for daily use. Thirty-two percent of students surveyed said they had used the drug in the past month, 46 percent in the last year, and nearly 60 percent at any time.

The survey, conducted by the University of Michigan's Institute for Social Research, provides an annual monitor of teen-age drug use trends. Each year since 1975, the institute takes a national sample of about 17,000 high school seniors in 130 public and private schools.

The major findings include:

* A drop in students' use of cigarettes, PCP, certain inhalants and tranquilizers, as well as marijuana. Daily cigarette use declined from 29 percent in 1977 to 20 percent in 1981.

* Little change in the use of alcohol, cocaine, heroin, barbiturates and LSD.

* A sharp increase in the use of stimulants, or uppers, and a slight increase in use of the sedative drug methaqualone, or Quaalude.

Overall, Johnston concludes that teen-age drug use appears to be "moderating," perhaps because youth today is less defiant. He attributes declining marijuana (and tobacco) use to increasing concerns about the health risks involved and changes in peer pressure.

For example, the number of seniors attributing "great risk" to regular marijuana use has grown over the last three years from 35 to 58 percent. Three-quarters of all seniors now think their close friends would disapprove of such behavior.

Despite improvements, however, the survey report notes that illicit drug use "is still extremely prevalent among American young people of high school age," probably the highest levels "to be found in any industrialized nation in the world."

In the graduating class of 1981, two-thirds of those surveyed admitted to at least some illicit use of a drug, a number the Michigan researchers consider a "conservatively low estimate."

Lifetime usage rates were 17 percent for cocaine, 11 percent for barbiturates, 10 percent for LSD, 10 percent for opiates other than heroin and 1 percent for heroin itself.

Alcohol use remains steady, with 6 percent reporting daily use. "Much more disturbing," said Johnston, is that "41 percent of all seniors admit to having had five or more drinks in a row at least once in the prior two weeks."

He is most concerned, however, about the "sharp rise in stimulant use." About one-third of all high school seniors say they have used amphetamines at some time, up from 26 percent a year earlier. And 16 percent said they have used stimulants in the last month, up from 12 percent in 1980.

Researchers are uncertain whether this is due to actual use of controlled, prescription-type amphetamines or so-called "look-alike" drugs marketed to look like them. Diet, stay-awake and pep pills are also widely promoted by mail order or sold in drugstores. Johnston reported a rise in both recreational and nonrecreational uses of these drugs.

Additional attention to the health risks of regular marijuana use is also expected later this week with the release of a National Academy of Sciences report.

Sources said the report will raise concerns about the effects on mental functioning and learning, adverse effects on perception and skilled performance that can interfere with driving, possible reproductive effects, and long-term lung damage.