WALTHAM, Feb. 16--Brandeis President Abram L. Sachar promised a closed student audience today that he would relieve the class overcrowding that set off a two-day boycott of courses here this week.

Sachar said he will try to create more general education courses for undergraduates and persuade the "ablest faculty members" to teach more undergraduate courses, according to Steven Kramer, editor of the Brandeis weekly newspaper.

Kramer said Sachar hinted in his speech that faculty members were spending too much time on research and graduate education and not enough on teaching undergraduates. But Kramer insisted that the student body does not blame overcrowding on the faculty as a whole.

Sachar said he considered the boycott unnecessary because a faculty committee had suggested remedial proposals before it began Wednesday.

Nicholas Rabkin, one of the boycott's organizers said last night that Sachar was "very tactful in placing the bulk of the blame on the faculty, but he seemed to ignore the fact there is administration responsibility."

Sachar's stress on faculty members teaching more courses showed "the Administration has not changed its myopic view," Rabkin said. Rabkin asked why the Administration couldn't take more action itself--by hiring more teachers, for example.

Students go back to classes tomorrow morning. At the very least, Rabkin said, the boycott has made the administration aware of the undergraduates' concern.

But another student thought the boycott "played right into Sachar's hands." Expressing what he called a "wide spread belief," the student said Sachar wants to get "much more work out of the faculty than he's getting now without raising salaries."

Kramer described Sachar's address in an interview tonight. After praising the students' conduct of the boycott, the President launched into a brief history of the 19-year old institution.

Sachar explained that since becoming a university 13 years ago, Brandeis has had to balance graduate and undergraduate teaching. Although he admitted graduate programs tie down professors who otherwise might teach undergraduates, Sachar defended Brandeis' university status. He pointed out that colleges like Reed, without extensive research facilities, are having trouble holding on to top notch instructors.

Sachar pledged that he would, for the present, withstand efforts to further expand graduate study at Brandeis.