NEW YORK (AP) _ ''Exploitative sex and gratuitous violence'' are becoming rampant on television and other mass media and must be reduced by industry and government controls, a National Council of Churches study said Friday.

Some television executives criticized the study, while others said existing self-regulatory policies were sufficient to curb excesses.

The report strongly opposed censorship but urged that the Federal Communications Commission resume oversight of broadcasting, through congressional action if necessary.

George Schweitzer, a CBS vice president, called the report a ''disappointing and frightening document'' advocating a ''blatantly repressive policy.''

He said ''it would turn the FCC into a mechanism for direct governmental review of the editorial process with ... unforeseeable consequences for some of our most cherished traditions.''

NBC and MTV, the cable TV music video channel, declined comment until they could study the 48-page report, but an ABC statement said its ''self- regulatory process'' enabled the network to meet its ''social responsibility in the review of entertainment programming.''

The report, dealing only with entertainment shows, deplored recent deregulation of the industry and the FCC's ''apparent indifference'' to the increasing ''amount and vicious character of the violence,'' left up to market forces alone.

The head of the study group, Rev. James M. Wall of Chicago, editor of the ecumenical weekly, The Christian Century, told a news conference:

''We're acting as friends and allies of the industry, but we're telling it to wake up and clean up its act, or lose those allies and let the harsh, censorial groups take over.''

The study group's two-year investigation also concluded that sexual and other violence in film, network television, cable TV, music videos and home video programming stirs ''anti-social and aggressive behavior'' among young and adult viewers.

''The quality of life in our society is threatened by the amount, intensity and graphic persuasiveness of this violence in the media,'' the council said. ''The situation is made more dangerous and offensive when the violence is couched in an erotic context.''

Among measures the study recommended to regulate the flow of ''exploitative sex and gratuitous violence'' in the mass media included a classification and rating system like that for motion pictures.

The report says self-regulation ''can only be a partial solution because without governmental regulation the industry's self-interest finally will take precedence over the public interest.''

The nine-member study panel spent two years gathering evidence and holding hearings, with testimony by various experts, including network producers, writers, actors and executives.

''Many of them don't like the schlock any more than we do, but they're all caught in the system,'' said the Rev. William F. Fore, director of the interdenominational council's communication commission. ''We aren't trying to zap anybody but to help them do a good job which we think they themselves want.''

For its conclusions that media violence leads to ''aggressive behavior by children, teen-agers and adults,'' the report cited accumulated findings by government commissions, the U.S. Surgeon General, the National Institute for Mental Health and various university researchers.

The report calls television the ''most pervasive of all media,'' watched an average six hours daily in 98 percent of American homes.

It blamed the ''prevalence of sexual violence and overall violence'' on three factors - monopoly control of programs by a ''handful of powerful companies,'' a ''drive for profits'' far exceeding that of most coporations, and failure of the FCC to exercise adequate oversight.

The report recommends that the FCC, by congressional mandate if need be, reassert its oversight, requiring broadcasters ''to once again exercise their responsibility to the public.''

The FCC also should be required to conduct annual open hearings about decisions on the content of entertainment programs, to assess the amount of violence and its effects.

''The messages media carry help create ourt world, at the same moment that they reflect it,'' the study said. ''The choices made by writers, directors, producers, distributors and sponsors all contribute to what our world shall become.''