The incident was reported around 10 a.m.
Los Angeles police spokesman Richard French said a woman was on a park trail when she noticed a man following her.
A short time later, the man began speaking to the woman in Spanish and then tried to attack her.
"She was able to get away from him," French said. "At this point, it does appear to be an attempted sexual assault."
The woman was taken to a hospital to be checked out but was not seriously injured, he said.
The assailant, described as being in his 30s, remains at large. No further description was immediately available.