Sen. Edward M. Kennedy (D-Mass.) unloaded a harsh new attack yesterday on President Carter's oil decontrol plan calling it a sham that will set poor against rich and worsen inflation.

Kennedy told a friendly commencement audience at Howard University here he found it "incredible" that a Democratic White House would push a program that would most adversely affect low and middle income Americans.

The Senator, awarded an honorary doctotrate by the university deep in the low income Shaw neighborhood stressed the "unfair" burden that he said Carter's decontrol plan would put on the poor.

"Is it fair to ask those who are poor to pay a much larger proportion of their income for energy than those who are more affluent?

"Is it fair to ask poor elderly citizens in Northeast Washington to shift to cat food so they can afford to pay their heating bill" Kennedy asked.

That question drew one of the warmest responses of the day heartly applause and a smattering of "that's right" from the crowd of 4,000 or more graduates, parents and friends in the Howard football stadium.

The White House meanwhile responded with minimal enthusiam to a suggestion from Senate Majority Leader Robert C. Bryd (D.W. Va.) that Carter hold a meeting with the congressional leadership to try once more to win passage of a standby gasoline rationing plan. The House rejected Carter's plan last week.

"The president would be willing to meet if Byrd thinks it will help." Stuart Eizenstat, Carter's chief domestic affair adviser, said yesterday, But we think the burden is now on Congress to come up with something."

Kennedy's renewed criticism of Carter - he mentioned the president's name only twice - seems certain to intensify congressional debate about the decontrol plan.

Kennedy and Gen. Henry M. Jackson (D-Wash.) are major crities of the plan that will take effect next month unless stopped by congress. In stages through September 1981 it would remove federal controls from the prices of domestically produced oil.

Kennedy repeated his theme that the Carter plan does not go far enough to tax "windfall profits" and that it does not require the industry to devote its new profits to exploration.

"Even the phrase 'decontrol' itself is misleading," Kennedy said. "It violates the truth-in-labelling law. It is not decontrol at all, There will still be controls. The only difference is that control over the price of American oil will be turned over entirely to the OPEC [Organization of Petroleum Exporting Countries] countries and the oil industry."

A better solution, he continued would be thore U.S. cooperation with developing nations to seek new oil deposits, while continuing efforts to curb energy usage in the United States.

"That is the fundamental mistake of the Carter administration on energy policy," he said "The answer to our crisis will be found by giving more power to competition, more power to the people, not more profits to Big Oil."

He called decontrol "the worst form of rationing, because it is rationing by price."

Another Kennedy question: "What possible gain can there be for America from an energy policy whose primary effect is to boost the already ample profits of the oil industry, put millions of consumers through the wringer, and sharpen the class divisions of our society?"

Byrd said yesterday Carter might still salvage a gasoline rationing plan if he would "get all the principal players together and talk it over."

Byrd phoned Carter to discuss the prospects for rationing plans Friday night, just after the president had blasted the House for rejecting his proposal. "I told him he could be a catalyst if he would get together" with the energy leaders in Congress.

Bryd said Carter had responded "amenably, with interest" to this suggestion. But Eizenstat, dicussing the Byrd proposal yesterday afternoon, did not sound very interested.

"Bryd asked him to get together with Tip O'Neill," the House Speaker, said Eizenstat. "Of course, anytime the leadership wants to meet with the president, he'd be glad to have a meeting. But we continue to think the burden is on the House."

Asked whether he expects the House to take any positive action on a rationing plan of its own, Fizenstat replied, "No."

A task force representing several federal agencies met at the White House Friday to talk about whether and how the administration might act to deal with possible gasoline shortages this summer.

Eizenstat said the group's first job is "to try to answer some questions about what we're facing. Do we have a shortage that is severe enough to require some special response, or is it a minimal shortage with panic buying on top of it?"

Eizenstat said the group will also consider options for dealing with a shortage, although "the House didn't leave us with a hell of a lot of choices."

One possibilty, Eizenstat said, is a nationwide version of the odd/even gasoline sales plan now in effect in parts of California.