In a video posted on YouTube, Assad is shown against images of other Syrian women, and children who are either dead or wounded, CNN reported Tuesday.
The video was produced by Huberta von Voss-Wittig, the wife of Germany's U.N. ambassador, and Sheila Lyall Grant, the wife of Britain's U.N. ambassador.
"We want her to speak out for the end of violence. That is what we want. Stop the bloodshed. Stop it now. We know this is a risk for you, but take this risk," Voss-Wittig told CNN.
Syria has been swallowed by violence for 13 months as an anti-Assad uprising spread after the government began a violent crackdown on protests. The United Nations estimates at least 9,000 people have died since the demonstrations began, while other organizations said the toll is greater than 11,000.
"Stand up for peace, Asma," the video's voice over said. "Speak out now. For the sake of your people. Stop your husband and his supporters. Stop being a bystander."
The London-born Asma Assad graduated from King's College with a degree in computer science. She was an investment banker for JP Morgan before marrying Bashar Assad in 2000, several months before he became Syria's president.
A cache of e-mails leaked to CNN indicated Asma Assad seemed to spend much of last year shopping online for costly jewelry, art, and furniture.
"No one cares about your image," the video said. "We care about your action."