The type of catastrophic health insurance plan some of his main economic advisers are urging on President Carter was attacked as "unacceptable" yesterday by Sen. Edward M. Kennedy (D-Mass.).

A catastrophic health insurance bill to insure Americans against the most serious and costly illnesses has been introduced by three senators - Russel B. Long (D-La.), Abraham A. Ribicoff (D-Conn.), and Bob Dole (R-Kan.).

Kennedy, leading congressional advocate of broader national health insurance, heads a Senate health subcommittee that will play a key role in considering any national health plan.

Long heads the Senate Finance Committee, which will play an equally important role. Economic advisers like James McIntyre, head of the Office of Management and Budget, and Treasury Secretary W. Michael Blumenthal have been telling the president the country can't afford any broad, inflation health insurance.

The president is expected to decide whether to ask Congress for "broad," "comprehensive" health insurance or for a narrower, so-called "targeted" plan in time to announce a set of health insurance "principles" late this month.

Some of "those who oppose" broad health insurance "say the only serious problem is catastrophic illness," Kennedy said in a talk prepared for delivery to the National Council of Senior Citizens.

"But catastrophic health insurance would make all our health problems worse," he maintained. "It would flood one small corner of the system with billions of new dollars," with "no way of controlling costs" or making other revisions."

Carter yesterday told the same group of senior citizens of his continued "commitment for a comprehensive national health care system."

But an aide said he "hasn't yet made up his mind" just what to ask for in the way of a bill, and whether it will set specific goals and target dates for a broad rather than a narrower plan.