An effort to make more doctors accept lower fees for their Medicare patients was defeated in the House Commerce Committee yesterday.

The attempt was made by Rep. Toby Moffett (D-Conn.) who said citizens over 65 are being forced to pay "millions out of their own pockets" by "a growing number of doctors" - Now six doctors out of 10 - who refuse to accept cut-rate Medicare fees as their full fee.

Moffett offered the measure as an amendment to an administration-backed hospital cost control bill the committee has been debating since June 6.

He said the elderly must pay doctors and hospitals 15 percent more in actual cash and they paid in 1966, when Medicare started. He wanted to require hospitals to bar any doctor who refuses what is called Medicare "assignment" - that is, refuses to mark a patient's bill "paid" after a Medicare fee that usually runs around 80 percent of the customary fee.

Rep. Dave Stockman (R-Mich.) argued that calculated in 1978 dollards, the elderly still paid only $460 out of their own funds in 1976, compared to $463 in 1966.

Moffett's amendment was defeated, 27 to 12, with many members arguing against acting without more deliberation. Some also pointed out that the subject is being investigated by the House Ways and Means health subcommittee, which was jurisdiction over Medicare.

Moffett - a supporter until yesterday of the hospital cost control measure - told reporters the committee action is one of several reasons he has now decided to vote against the bill, a measure he said has been "gutted" by many amendments backed by labor, hospital and medical groups who oppose hospital cost controls.