Health, Education and Welfare Secretary Joseph A. Califano Jr., unable so far to get Congress to limit hospital costs, yesterday ordered new regulations to cut federal health care spending by $393 million next year, changing the way HEW pays for care for Medicare and Medicaid patients.

Affecting hospitals and other health care facilities, the changes include:

Limits to Medicare's and Medicaid's share of malpractice costs, expected to save $310 million in fiscal 1980, starting in October, Califano said.

A new schedule of payment limits for hospitals' daily operating costs.

Amendments to regulations limiting reimbursable costs for federally covered patients.

Payment limits for home health care.

On malpractice, Medicare now pays 40 percent of a hospital's malpractice costs if Medicare patients make up 40 percent of the hospital's load, a common figure. But a recent HEW study shows that malpractice awards to the 65-and-over Medicare patients are much lower than those to the general population, because awards are based on life expectancy and income potential.

Starting July 1, but affecting hospitals according to when their cost-reporting periods begin, Medicare will pay only the actual costs of malpractice premiums, self-insurance or losses attributable to Medicare Patients.

HEW Thursday also proposed new ceilings on payments for care in skilled nursing facilities, to save some $95 million in fiscal 1980 if this proposal, published in the Federal Register, is also coverted into regulation.