Sen. Gordon J. Humphrey (R-N.H.) assailed Health and Human Services Secretary Otis R. Bowen yesterday for firing antiabortion activist Jo Ann Gasper from her job as head of the $142.5 million Family Planning Program and urged an investigation into her dismissal.

"Clearly, the secretary of HHS is thwarting the president's policies and he may be in violation of the law and department regulations," said Humphrey, who called on HHS Inspector General Richard P. Kusserow to look into the events leading to the dismissal.

Bowen fired Gasper, a political appointee, Thursday after she repeatedly refused orders from her superior and then from Bowen to renew training grants totaling $300,000 to two Planned Parenthood groups. She argued that she needed time and authority to investigate whether the groups' advocacy of abortion makes them ineligible for the money.

Bowen said he agrees with President Reagan's "right-to-life" views and opposition to abortion but that Gasper was guilty of insubordination in refusing a direct and lawful order to renew the grants.

Gasper, speaking at Humphrey's news conference, said, "Secretary Otis Bowen fired me because I refused to fund abortionists. I am 'pro-life' and had been trying to force Otis Bowen to live up to the president's commitment" to battle abortion wherever possible.

She said that instead of pressing to "remove all taint of abortion and abortion-related activities" from the Family Planning Program, Bowen made "a closed-door deal" with Senate supporters of abortion rights. "Nothing was to be done. It was to be the status quo. The entanglement of abortion and abortion-related activities with the Family Planning Program was to continue," Gasper said.

In January, Gasper, without charging that Planned Parenthood was using federal funds for abortion, issued an order to oust all Planned Parenthood groups from the program because of general advocacy of abortion, but it was rescinded by higher officials. She contended that many steps could be taken administratively to tighten the program.

Gasper said she may challenge her dismissal through the Merit Systems Protection Board or under the so-called conscience clause, which she said bars discrimination against employes because of their views on abortion.

HHS officials had become increasingly exasperated with Gasper, believing that she was unilaterally attempting to impose restrictions in the Family Planning Program that went beyond what could be done without changes in the law.

Underlying the dispute is the effort by antiabortion groups to bar from the Family Planning Program any organization that performs, advocates or favors abortion, even if it uses only nonfederal funds to do so.

The program provides federal grants to fund local birth-control and family-planning clinics but the money may not be used to perform or advocate abortion. The restriction has never been interpreted to bar an organization from the program for using its own money for such purposes.

Reps. Jack Kemp (R-N.Y.) and Robert K. Dornan (R-Calif.) and Sen. Steve Symms (R-Idaho) also criticized the dismissal of Gasper.

There was no comment from Bowen or Kusserow.