Los Angeles police say the attack happened in the early morning hours on Monday. The girl was walking near Melrose Avenue and Alta Vista Boulevard at about 1 a.m. when the suspect began walking alongside her.
Police said he started talking to the victim before pulling her into an alley and trying to rape her.
The girl screamed for help, prompting several nearby residents to call 911.
Webb ran off and was arrested about 10 hours later.
Investigators say they believe he may be responsible for other such attacks and are asking potential victims to come forward.
Webb has a tattoo on the back of each hand. One reads, "Honey" and the other reads "Combs."
City News Service contributed to this report.