The Commerce secretary will play a more significant role in preparing economic policy, President Carter's nominee for the post insisted yesterday.

Philip Klutznick, Carter's choice to succeed Juanita M. Kreps as Commerce secretary, assured the Senate Commerce Committee that the Treasury has modified its policies in order to include Klutznick in its regular economic policy-making discussions.

"I was not only told I would be a full participant, but I made it clear that I expected to be," Klutznick told the committee during a confirmation hearing.

Former Treasury secretary Michael Blumenthal had excluded Kreps from the weekly meetings of the Economic Policy Group, a high-level panel that includes the chairmen of the Council of Economic Advisers and Federal Reserve Board and several Cabinet members.

But Blumenthal's successor, G. William Miller, has revised those policies, Klutznick said, assuring the committee that he "will be a full member" of that group.

Sen. Howard Cannon (D-Nev.) said the committee would await a ruling from the Office of Government Ethics on the type of trust Klutznick could use to shield himself from potential conflicts of interest before taking a confirmation vote.

Asked whether he would be a full-time Commerce secretary or a Cabinet member in place to promote Carter's re-election, Klutznick said such a charge was demeaning. Klutznick said his "first obligation" is to be Commerce secretary.