U.S. Court of Appeals Judge Abner J. Mikva, one of the court's leading liberals, has agreed to curtail his activities as chairman of an American Bar Association committee after a conservative lobbying group complained that Mikva had violated judicial ethics.

The arrangement restricting Mikva's role as chairman of the ABA's Individual Rights and Responsibilities section was reached without a formal investigation by the court, and no ruling was made on judicial misconduct allegations brought by the Washington Legal Foundation.

Chief Judge Spottswood W. Robinson III said in a decision issued June 26 that Mikva had agreed to discontinue his involvement in recruiting new members for the section but would remain as its chairman until his one-year term expires next month.

The foundation, which has been involved in numerous conservative efforts on issues affecting the judiciary, complained that Mikva's activities with the group "compromised the impartiality of his judicial office."

Mikva's efforts to recruit dues-paying members to the ABA, the foundation argued, "created a strong appearance of impropriety" under general prohibitions against judges soliciting funds.

A lawyer for the foundation, George C. Smith, said yesterday that officials there were "partially pleased" with the outcome of the complaint but were still considering whether to appeal Robinson's decision. The foundation had asked that Mikva be forced to resign as section chairman.

"The point we were stressing is that there is a problem when one who is sitting as a federal judge is taking an active leadership position as chairman of a group with controversial positions on sharply divided issues," Smith said. "We think that certainly presents a problem as far as the appearance of impartiality."

The Individual Rights and Responsibilities section of the ABA has been a strong advocate of civil rights legislation as well as federal programs supporting legal assistance for the poor and disadvantaged. It is one of more than 20 ABA national committees focusing on specific areas of legal interest.

Mikva, 60, said yesterday that he was satisfied with the court's action, saying that his role in recruiting for the ABA section had been limited.

"My bottom line," Mikva said, "is that if the worst thing I've ever done in my life is recruit lawyers to the American Bar Association, I've led a pretty uninteresting life."

The dispute arose after reports in legal trade journals described Mikva's appearance before lawyers' groups in Chicago last October. He urged the lawyers to join the 2,700-member Individual Rights and Responsibilities section, saying, "It's a battle for the soul of the American Bar Association."

The legal foundation filed its complaint in February. Mikva, a former Democratic Illinois congressman who was appointed to the bench in 1980 by President Carter, said he had been unaware that recruiting dues-paying ABA members might fall under a general prohibition on judges soliciting funds.

In some quarters, the foundation's complaint against Mikva was seen as another round in an ongoing battle between liberals and conservatives over ideology in the judiciary.

Last year, the foundation sued the ABA over its use of a secret screening process to evaluate presidential nominees to the federal bench.

Some conservative judicial candidates have been blocked by the screening process. The foundation's lawsuit is pending.