WASHINGTON — The embattled president of Planned Parenthood on Tuesday forcefully disputed what she called “outrageous accusations” by Republicans that her organization profits from the sale of fetal tissue, telling Congress that the charges were “offensive and categorically untrue.”

In testimony before the House Oversight and Government Reform Committee, the president, Cecile Richards, faced off against conservative lawmakers who are seeking to strip federal funding from Planned Parenthood after videos released by anti-abortion activists purported to show officials from the health group trying to sell fetal tissue. It was her first appearance before Congress since the issue exploded in July.

Ms. Richards said that the videos had been edited by the activists to mislead, and that Planned Parenthood facilitated the donation of only a small amount of fetal tissue and recouped only reasonable expenses as allowed by the law.

“The latest smear campaign is based on efforts by our opponents to entrap our doctors and clinicians into breaking the law — and once again, our opponents failed,” Ms. Richards said.