Liberal and conservative groups on opposing sides of the issue yesterday criticized new rules being considered by the Reagan administration that would require parents to be informed when teen-agers under 18 get prescription birth control products.

Internal memos and drafts of the proposal prepared by the Department of Health and Human Services indicate that Secretary Richard S. Schweiker's advisers disagreed about the regulations and worried about the reaction of conservative "outside groups and individuals" that were pushing the government to take stronger actions on "parental involvement."

The proposal, which has been sent to the Office of Management and Budget for final approval and is still under negotiation, would require family planning agencies receiving federal funds to notify the parents of minors under 18 who seek contraceptive prescription drugs and devices. The notification would be required within 10 days after the services are provided.

The draft proposal argues that the only exceptions would be when the "project director determines that notification would have adverse physical health consequences for the minor." Agencies would be required to keep records of their determinations.

In addition, state laws that are more restrictive would take precedence. One example is a Utah law that requires the prior consent of parents when publicly subsidized family planning services are involved.

Documents obtained by The Washington Post indicated that within HHS, the general counsel, Juan A. del Real, had initially argued that the "strongest" legal approach was to simply encourage family participation but not require it.

But Marjory Mecklenberg, a former anti-abortion activist who directs the department's population affairs activities, apparently won the fight, arguing for the stronger notification requirement on grounds that parents should be informed about prescription devices that affect the health of their children.

She also warned, in a memo, that "many outside individuals and groups will be deeply disappointed if this administration fails to significantly increase parental involvement."

A spokesman for Schweiker said that the decision was not made on political grounds but on Schweiker's "personal conviction" that "parents should know when one of their children under the age of 18 is being given a prescription drug or device of this kind."

Officials for private and public family planning organizations yesterday expressed concern that the administration's proposal would discourage sexually active teen-agers from seeking birth control devices and thus result in more unwanted pregnancies, as well as hamper the agencies with additional red tape.

In addition, said Asta Kenney, a spokesman for the Alan Guttmacher Institute, a special affiliate of Planned Parenthood, it would override "more progressive" state laws. She said that 30 states and the District of Columbia have passed legislation affirming the rights of minors to obtain family planning services on their own consent.

"It really is an egregious violation of the whole public health policy, with unfortunate consequences in terms of teen-age pregnancies, which inevitably are going to increase as a result of such a policy," Kenney said.

Dr. James Kenley, Virginia's commissioner of public health and president of the Association of State and Territorial Health Officers, predicted that if the proposal goes through it will get "very negative" reaction at the state level. "This is an unnecessary intrusion on states' rights running counter to what we're led to believe is the whole thrust of the administration," with "unnecessary expense and burden."

He agreed that it will "absolutely discourage" teen-agers to seek birth control assistance. "They're not going to go to an agency that's obligated to squeal on them."

A staff aide to Rep. Henry A. Waxman (D-Calif.) also argued that the proposal ran "contrary to the intent of Congress," which earlier this year said that family participation should be encouraged "to the extent practical." A House-Senate conference report stated that "family involvement is not mandated."

Two organizations felt, on the other hand, that the proposal did not go far enough, that it should require prior parental consent. Judy Brown, of the anti-abortion American Life Lobby, complained that parental consent was needed for both family planning and abortions for teen-agers and that the administration proposal would "promote more abortion among young people." The United Families of America said that the proposal did not "go nearly far enough."