President Carter said yesterday that while he has made mistakes in his initial dealings with Congress he remains confident that the relationship between the White House and Capitol Hill will be such that vetoes of legislation will be rare.

At his first press conference since his inauguration, the President conceded that there is some cause for the complaints by members of Congress over the lack of consultation with them by White House officials.

"We've had made some mistakes," he said, citing particularly problems in filling top administration jobs.

"The handling of personnel appointments, trying to get the right person in the right position at the right time, is a very, very difficult question," Carter said. "We have not been adequately careful in the initial days in dealing with the Congress."

But, the President added, through frequent meetings with the congressional leadership and "a thorough discussion of our differences . . . we have made a great deal of progress in correcting those early mistakes."

Carter said the best was to avoid frequent use of the presidential veto - a device used often by his predecessor, President Ford - is to "work intimately with the Congress in the initial stages of the development of legislation."

While saying vetoes may be necessary at times and that he would veto a drastically revised version of his $31.2 billion economic stimulus package, the President added, "The number of vetoes in prospect would be very small."

Even as Carter spoke, however, the rumblings of discontent over White House-congressional relations continued on Capitol Hill. Members of the House Democratic Steering and Policy Committee met yesterday afternoon with Vice President Mondale and White House congressional relations chief Frank Moore to insists that they be consulted in advance on policy and planning matters.

Congressional sources said the committee, which includes the House Democratic leadership, told Mondale and Moore they do not want to oppose a Democratic President but may be forced to occasionally if they are not consulted in advance about issues.

The President continued his wooing of Congress yesterday morning at a weekly breakfast meeting with the Democratic congressional leadership to which Sen. Abraham A. Ribicoff (D-Conn.) and Rep. Jack Brooks (D-Tex.) - the committee chairmen who will handle the administration's government reorganization legislation - were invited.

Brooks had been critical of Carter's reorganization proposal, and after the meeting House Speaker Thomas P. (Tip) O'Neill said neither Brooks nor Carter "showed any flexibility." But O'Neill also expressed confidence that Brooks will be "very decent" in handling the legislation.

While Carter was calling for better congressional relations, he also displayed at the press conference a deft ability to throw potential problems back at the congressional leadership. Asked why Rep. Shirley Chisholm (D-N.Y.), the secretary of the House Democratic Caucus, has not been invited to the weekly meetings with him, the President replied that O'Neill issued the invitations and the question should be put to him.

Carter appeared relaxed and exceptionally well prepared for his first press conference as President. He made no announcements to begin the press conference, saying he wanted to devote as much time as possible to answering questions.

On energy, the President issued one of his sternest warnings to date, saying the national energy policy he will propose by April 20 will "require substantial sacrifices on the part of the American people."

While flatly opposing the nationalization of the oil and gas industry, Carter added that he will seek to prevent them from gaining "unwarranted profits when we cut back on consumption and when we encourage production."

If the energy policy is not "fair and comprehensive," he said, it will be rejected by the public and Congress. "I don't intend to fail in this," the President said.

On other matters, Carter:

Pledged to aviod any "semblance of dishonosty or concealing of any information the public has a right to know" so there is not a fear of scandals similar to Watergate erupting in his administration.

Repeated his support for the pending pay raise for members of Congress so long as it is accompanied by strict ethics legislation.

Said the Commerce Department will seek a change in the formula for allocating public works funds so that the money is targeted as areas with the highest unemployment.

The President began the press conference by reiterating his promise to hold at least two such sessions a month.

"I look forward to those confrontations with the press to kind of balance out the nice and pleasant things that come to me as president," he said.