Joseph A. Califano Jr. said yesterday he opposes spending federal funds for abortions under Medicaid, a national health insurance plan, or any other program he would manage as the prospective Secretary of Health, Education and Welfare.

During a day of questioning on the issue, Califano reiterated several times that he believes abortions are morally wrong and should not be financed by the government.

However, he told two Senate committees that so long as the law permits federally financed abortions he would enforce it. And he said that he does not favor a constitutional emendment that would prohobit abortions.

President-elect Jimmy Carter's nominee to head HEW, Califano was thrust into tthe emotional issue by probing questions thrown at him by members of the Senate Finance Committee and the Senate Labor and Public Welfare Committee.

His most persistent queationer, Sen. Bob Packwood (R-Ore.), told him his views would mean that poor women who cannot afford private abortion costs would be denied their right to terminate a pregnancu.

"What you're saying is that if she's poor and can't afford a private abortion, then it's just tough luck, isn't it?" Packwood asked.

Sen. Jacob K. Javits (R-N.Y.) and other senators predicted a long and contentious struggle over the issue. "It's going to be a very hard road for you because of the depths of your feelings." Javits told Califano.

Between 250,000 and 300,000 abortions are financed each year under the federal medicaid program, which is administered bu HEW.

Last year, Congress amended the HEW appropriations bill to prohibit virtually all abortions under the Medicaid program. However, last October U.S. District Court Judge John F. Dooling in Brooklyn ruled that prohibition unconstitutional, saying it denied to the poor a right guaranteed by prevented states from banning abortions.

Dooning's decision is being appealed, and, pending a final resolution by the Supreme Court, Medicaid-financed abortions are still being performed.

Although Medicaid is the immediate issue, the abortion question will arise in other programs operated by HEW. Califano said yesterday the Carter administration expects to propose a new national health insurance plan early in 1978. He said he would oppose attempts to finance abortions through that plan.

Califano made only one exception. He would favor federal financing of abortions in cases where the mother's life is endangered by the pregnancy.

He said his administration would actively seek alternatives to abortion - a reliance on such programs as day care centers, foster homes, new adoption reforms and better sex education.

He emphasized that he and Carter agree on the issue. "He and I come to it from different cultural and social and religious backgrounds, but we come to the same position," he said. "Abortion is wrong and federal funds should not be used . . . But if the courts say that federal funds shall be provided, I'll enforce the law just like any other law."

Califano was warmly received by both committees, particularly by Democrats with whom he worked in the mid-1960s, when he was President Johnson's top aide for domestic issues. Some of his positions, however, were at odds with senators from both parties.

Calicano defended busing as the proper tool in some school desegregation cases, but said that under hs reign HEW begin a search for other methods.

"Busing has worked very well in some cases," Califano said, citing the desegregation of schools in Prince George's County, Maryland, as an example.

He told the Labor Committee that he has "grave reservations" about replacing the narrow categorical-aid programs in HEW with block grants, which give states and local governments a major voice in determining how federal money is spent. Substituting block grants for the long-established categorical programs was a main feature of the Nixon-Ford administration, and was supported by Republicans on both committees.

Califano said the categorical programs assure direct benefits to the recipients, such as the poor, blind and physically handicapped.

Califano said he had an "open mind" on the issue of creating a separate department of education, but indicated that he has strong doubts about the administrative wisdom of such a change. "I have written that one thing we don't need is another department reporting directly to the President," he said.

Carter has instructed him to present a welfare reform proposal to Congress this year. Califano declined tosay what his approach would be, but told the spending-conscious Finance Committee that if would undoubtely result in spending more on welfare than it now done.