A Senate Appropriations subcommittee voted yesterday to block President Reagan's tough new antiabortion regulations for the federal Family Planning Program.

The action is the latest move in a long dispute resulting from efforts by abortion foes to tighten antiabortion provisions in the program. They contend that the program channels women to abortion clinics.

The key provision of the new regulations, proposed Sept. 2 and not yet in effect, would bar any federally funded family planning clinic from informing a pregnant woman that abortion, as well as keeping the baby or putting it up for adoption, is one option for handling an unintended pregnancy.

The amendment to kill the new rules was approved by voice vote. It was added to a fiscal 1988 appropriations bill for the Health and Human Services Department by Sen. Lowell P. Weicker Jr. (R-Conn.), who has frequently expressed the view that it is medically unethical to fail to inform a pregnant woman of all her options.

"Congress has always intended the Family Planning Program to be comprehensive and this restates that intention," Weicker said after the vote.

But Gary L. Bauer, domestic adviser to the president and a strong opponent of abortion, said, "If Congress wants federal money to go for promoting and counseling abortion, it ought to step up and vote to do it" by a direct amendment to the program "instead of playing this sort of parliamentary game."

The 1970 Family Planning Act, authorizing grants to support clinics giving contraceptive, fertility and other family planning advice to poor women, expressly barred any federally funded clinic from performing abortions. But long-standing program rules require such clinics to tell pregnant women that abortion is one option and, if they request, to provide them with a list of abortion clinics operating outside the program with their own nonfederal funds. The new regulations would reverse this and forbid information about such options.

William W. Hamilton Jr. of the Planned Parenthood Federation of America and Scott Swirling of the National Family Planning and Reproductive Health Association, which oppose the president's regulations, expressed satisfaction with the Weicker amendment. Hamilton said he thinks it will be supported by the full Appropriations Committee next week.

The National Right to Life Committee, a strong supporter of the proposed regulations, vowed to fight the Weicker amendment and hinted that if the amendment is retained, a long and bitter debate would ensue that could threaten the HHS bill.

"This appropriations bill has many obstacles to overcome. And this provision is a long way from becoming law," said legislative director Douglas Johnson.

Family Planning funds under the bill would be $146 million in fiscal 1988.