The appeal to Obama comes as he travels the nation and lobbies Congress for new gun legislation in the wake of the Newtown, Connecticut, school shooting.
"We are making this call collectively that the president bring the weight of his bully pulpit and bring resources," T. Lane Grant, Rainbow/PUSH Coalition, said.
"We have a modern-day Sandy Hook every day in Chicago. We didn't have 20 kids killed in one place. But we had 26 kids shot at Harper School alone," Bishop James Dukes, Helping Hands of Englewood, said.
No one has been charged with Pendleton's murder. She was gunned down in a South Side park just a mile from the president's Chicago home. Just days before she was shot to death, she marched with the band during Obama's Washington, D.C. inauguration.
"The area of Roseland and Englewood is where he was an organizer, so it would be so meaningful. So we reach out to him not as a political challenge, but as a moral appeal," the Rev. Jesse Jackson said Tuesday.
"He has to create a big tent. He has to reach out to Republicans as well as conservative Democrats," Laura Washington, political analysis, said. "He doesn't want to aim this at urban communities. He doesn't want to aim this unfortunately at the communities that are being most affected by it."
"I miss her pink lips. It was like something we would talk about all the time," Cleopatra Pendleton, Hadiya's mother, said. "You know how, like, when your baby's born, you look at your child and it's just that thing that stands out."
In her first interview, Pendleton's mother, Cleopatra, said she hopes the $40,000 reward will lead to an arrest. "Someone out there that has a moral fiber --you know -- just some moral fiber and is not condoning this behavior because it is not OK," Cleopatra Pendleton said.
"Our children are frightened. They are traumatized; 516 deaths last year," Rev. Jackson said.
There is an online petition urging president Obama to attend Pendelton's funeral, which is set for this Saturday, February 9.