Six former high-ranking Pentagon officials of the Carter administration said yesterday they supported the high levels of defense spending proposed by President Reagan but were critical of where the new administration was putting the money.

The group, which calls itself "Democrats for Defense" and includes former deputy defense secretary W. Graham Claytor and former undersecretary Robert W. Komer, said the administration should:

Drop plans to build the new B1 bomber;

Not waste money on defense against bombers when the real threat is from missiles;

Not build two new nuclear-powered aircraft carriers when less expensive vessels might suffice.

Instead, the group contended that more money should be spent to beef up the combat readiness of existing forces and to buy more jet transports to move these troops quickly to trouble spots.

The group, which held a news conference here yesterday, also was attempting to deliver a message to congressional Democrats, who will have to take positions on the controversial new defense budget at a time when they see both a demand for cuts in government spending and a need for a strengthened national defense.

"We are fearful," Komer said, "that not enough Democrats will be arguing for a strong defense."

John G. Kester, a former special assistant to ex-secretary of defense Harold Brown, warned that "the Democratic Party must not fall into the trap of thinking that defense is not a legitimate need."

The group voiced general support for the proposed level of defense spending next fiscal year and for Reagan's plan to add some $167 billion to previously planned expenditures over the next five years.

But they were sharply critical of the "huge Reagan tax cuts and resulting 1983-85 deficits," saying these were certain to "make defense the obvious target" for compensatory budget cuts.

The group essentially argued that if Congress does make cuts, it should go after specific programs, not the general readiness accounts.

The Carter administration long opposed the $30 billion B1 program, arguing it was wiser to wait for the more advanced Stealth radar-evading bomber.

Walter B. Slocombe, a former deputy to Komer, argued that improved defense against enemy bombers was the wrong priority at a time of severe budgetary pressures, because the real threat was from missiles.

The group was divided on the proposal for two new aircraft carriers at a cost next year of $6.8 billion.

Claytor, who also served as Navy secretary under Carter, said the carriers should have conventional power rather than nuclear, at a saving of about $1 billion each.

All other officials argued either for building only one carrier or scrapping both and putting the money into more and smaller vessels.

Komer was sharply critical of the themes and tone laid out earlier this week in Defense Secretary Caspar W. Weinberger's first report to Congress on defense policy.

Komer said the report's lack of emphasis on the NATO alliance in western Europe, combined with massive new investment in the Navy and on maritime superiority, "looks more like a unilateral, go-it-alone approach."

Rep. Les Aspin (D-Wis.), a frequent but respected critic of Pentagon programs, also termed Weinberger's report "disappointing."

From the congressional standpoint, Aspin argued, the key issue is: "Do they have a policy? Do they know what they are talking about?"

The answer this year, for the first time, he said, is "No."

Aspin said Weinberger's approach has no real "philosophical underpinning," no detailed analysis of what threats U.S. forces face and what is needed to cope with the threats.

"The administration is asking for the biggest and fastest peacetime defense build-up since 1940," Aspin said. "More than ever, it is important that the various pieces of the defense build-up fit together."