WASHINGTON - After a week of protests by conservatives, an abortion-rights group said last night that it is withdrawing a television advertisement linking Supreme Court nominee John G. Roberts Jr. to violent anti-abortion activists.

"We regret that many people have misconstrued our recent advertisement about Mr. Roberts' record," said Nancy Keenan, president of NARAL Pro-Choice America.

"Unfortunately, the debate over that advertisement has become a distraction from the serious discussion we hoped to have with the American public," she said in a letter yesterday to Sen. Arlen Specter, a Pennsylvania Republican, who had urged the group to withdraw the ad.

Specter, himself an abortion-rights supporter as well as chairman of the Senate Judiciary Committee that will question Roberts next month, earlier yesterday had called the ad "blatantly untrue and unfair."

The NARAL ad criticizes Roberts and links him with violent anti-abortion protesters because of the anti-abortion briefs he worked on as a government lawyer.

"The NARAL advertisement is not helpful to the pro-choice cause which I support," Specter said in a letter to Keenan.

Keenan's response said the group will replace the ad with one that "examines Mr. Roberts' record on several points, including his advocacy for overturning Roe v. Wade, his statement questioning the right to privacy and his arguments against using a federal civil rights law to protect women and their doctors and nurses from those who use blockades and intimidation."

The original ad has been airing on broadcast television in Maine and Rhode Island and on CNN.

At least one television station had refused to run the ad.

Mike Young, vice president and general manager of WABI in Bangor, said his station ran the ad before deciding to pull it yesterday after receiving a challenge from the Republican National Committee.

"After careful, thoughtful analysis, we determined the ad was at worst false, and at best misleading," he said.

Conservatives and Roberts supporters have been calling all week for NARAL to pull the ad.

NARAL had planned a $500,000 campaign to show the ad for two weeks.