Hadiya Pendleton was killed in a Chicago park by a gunman who apparently was not even aiming at her as she talked with her friends.
Chicago police said Hadiya, who was in a marching band at this month's inauguration, was in a park about a mile from Mr Obama's home in a South Side neighbourhood on Tuesday afternoon when a man opened fire on the group. Hadiya was shot in the back as she tried to escape.
White House press secretary Jay Carney said the president and first lady Michelle Obama's thoughts and prayers were with Hadiya's family, adding: "And as the president has said, we will never be able to eradicate every act of evil in this country, but if we can save any one child's life, we have an obligation to try when it comes to the scourge of gun violence."
The city's 42nd killing is part of Chicago's bloodiest January in more than a decade, following on the heels of 2012, which ended with more than 500 murders for the first time since 2008.
It also comes at a time when Mr Obama, spurred by the Connecticut school massacre in December, is actively pushing for tougher gun laws, though he faces ardent opposition from the National Rifle Association and its allies in Congress.
Hadiya's father Nathaniel Pendleton spoke at a Chicago police news conference yesterday, held at the park where his daughter died. "He took the light of my life," Mr Pendleton said, then speaking directly to the killer, said: "Look at yourself, just know that you took a bright person, an innocent person, a non-violent person."
He and Hadiya's mother and 10-year-old brother were consoled by Superintendent Garry McCarthy of Chicago police .
Hadiya was a bright girl who was killed just as she was "wondering about which lofty goal she wanted to achieve", her godfather, Damon Stewart, said. Hadiya had been a majorette with the King College Prep band.
In Chicago, gangs routinely and often indiscriminately open fire. Mayor Rahm Emanuel and Mr McCarthy are pushing for tougher local, state and national gun laws and longer prison sentences for offenders.