As liberal criticism of his budget proposals mounted, President Carter yesterday defended his recommendations to cut Social Security benefits and increase defense spending, predicting that these and other aspects of his budget will "stand the test of the most intense scrutiny."

"I have not robbed the poor or the deprived or the social programs in order to provide for defense," the president told a nationally televised news conference.

But even as Carter spoke, Sen. Edward M. Kennedy (D-Mass.) accused him of employing "misleadingly low" budget figures for increased defense spending, while the liberal Americans for Democratic Action issued a broad blast at the budget, calling it "a bum deal for the nation."

Kennedy charged that the Carter budget "pads" earlier defense spending figures and that the president has actually proposed to increase defense spending by more than 4 percent above the inflation rate, not the 3.1 percent claimed by administration officials.

"I have no apology to make for a strong, adequate defense, nor for the allocation of funds necessary to insure a strong and adequate defense," the president told the news conference.

He also said he has kept his 1976 campaign promise to cut defnese spending by $5 billion to $7 billion, although the Pentagon's budget has risen steadily during his two years in office. Without elaboration, he said the administration has achieved "savings" of more than $5 billion in military spending.

One of the more controversial budget proposals Carter sent ot Congress this week was for about a $600 million reduction in Social Security payments, largely involving disability benefits, student benefits and payments to widows.

The president conceded that "this is not a politically popular proposal," but defended it as desinged to eliminate "duplicating services."

"In the long run," he said, "we have got to make sure that, within the limited Social Security funding, which is derived fron those who are working now, that the allocation of funds goes to those who need it most, who don't have any other way to derive benefits. And with a linited amount of money, it is imperative that the system be efficient and that benefits go where they are most needed."

Carter added that the budget provides a 12 percent increase in spending for the elderly so that "we have not in any way overlooked the genuine needs of the elderly or retired people in this nation."

On other topics during the 30-minute news conference, the president:

Refused to say whether he would debate a Republican opponent in 1980 if he seeks reelection, saying it is "too early" to discuss the next presidential campaign.

Said he does not expect the slogan of his State of the Union speech to Congress Tuesday -- a "new foundation" -- to survive in the American political lexicon. But Carter called the slogan " good one" to describe his presidency. "Many of the decisions that we have made and are making do not pay off in immedicate political benefits, but it is an investment at the present time for future dividends for America," he said.

Said some members of the Senate, whom he did not name, have not cooperated enough with his efforts to appoint blacks and other minorities and women to federal judgeships. The White House currently is in a dispute with Sen. Harry F. Byrd Jr. (Ind.-Va.) over the issue of federal judicial appaintments.

Said when asked about rising oil company profits, that he hoped to keep "all industrial profits at a reasonable level, with none being exorbitant." However, he did not suggest that he would seek to curb oil company profits if he considered them excessive.