President Reagan nominated a senior Justice Department aide yesterday to a seat on the U.S. Court of Appeals in Washington, heading off what promised to be a bitter confirmation fight over the official's possible appointment to a seat on the federal appeals court in Richmond.

The aide, 36-year-old Kenneth W. Starr, legal counsel to Attorney General William French Smith, had been considered by the administration for a vacancy on the 4th U.S. Circuit Court of Appeals in Richmond.

Reports of that plan had drawn immediate and sharp criticism from Sen. John W. Warner (R-Va.) and all but one of the Republican congressmen from Virginia. They contended that the vacant seat should be filled by a Virginia judge and said privately that Starr, who lives in McLean, was not qualified for the appointment.

The White House's decision to name Starr to the D.C. appeals bench was seen yesterday as a victory for Warner, who had worked for months to block Starr's nomination to the Richmond bench. It could allow Reagan to name one of Warner's three nominees to the 4th circuit, leading to the possibility that the woman could be named a federal district court judge in Virginia for the first time.

Warner, who is up for reelection next year, had warned administration officials, first privately and then later publicly, that he would oppose the nomination, in part because Starr was not a Virginia native (he is from Vernon, Tex.) and because of Starr's inexperience and relative youth.

The opposition to Starr's selection in Virginia was so intense that a letter signed by all but one member of the delegation was sent last March to Reagan voicing their strong support for any of Warner's nominees. Warner had sent the White House the names of three currently sitting U.S. District Court judges--J. Calvitt Clarke Jr. of Norfolk, Albert V. Bryan Jr. of Alexandria and Glen M. Williams of Abingdon in Southwest Virginia.

Warner said yesterday he would not comment on Starr's nomination until hearings on the appointment. "I have been in frequent consultation with senior White House staff regarding the vacancy on the 4th circuit," he said. "My views have been taken into consideration as the president neared his decision on which individual he will nominate to fill the 4th circuit" vacancy.

Administration officials for months have said privately that it made more sense to put Starr, a conservative in tune with the administration's views, on the more liberal and prestigious D.C. appellate court than to name another conservative to the court in Richmond.

In addition, several officials pointed out, today's move could clear the way for nominating one of Warner's choices, and would create an opportunity for Reagan to make another appointment, possibly a woman, to a federal district court seat in Virginia. Warner has indicated a leading nominee for such an opening is U.S. Attorney Elsie Munsell of Alexandria.

Administration officials said yesterday that while there might be some opposition to Starr's appointment, it was a certainty that his nomination would be confirmed by the Senate. Starr would fill a vacancy created last April when D.C. Court of Appeals Judge George E. MacKinnon assumed senior status.

Starr, considered an able and extremely bright lawyer, is a graduate of George Washington University and Duke University law school. He clerked for a federal appeals court judge after law school and then for Chief Justice Warren E. Burger for two years. After that, Starr went to work for William French Smith's Los Angeles law firm, Gibson, Dunn & Crutcher, before coming to Washington to assume the job of legal counsel to the attorney general.

The open seat on the 4th circuit was held until late last year by Judge John D. Butzner of Richmond, who has taken the semiretired status of a senior judge.