Danielle Kang shot a five-under 67 in the final round of the ANA Inspiration, having reported a death threat to police the previous evening.
Kang, in Rancho Mirage, California for the first major of the LPGA season, dined in a sushi restaurant with her mother and a friend on Saturday, having carded a 77 that day.
The 22-year-old claimed that she was harassed by two men, who shouted: "You played like s***" and: "I'll f***ing kill you."
"I was actually scared for my life," Kang is quoted as saying by the Golf Channel.
"I am kind of thinking I'm going to be stabbed if this guy has a knife. Nobody [in the restaurant] did anything. He [one of the men] was shouting. Everyone stopped eating.
"I've never seen a man so upset in my life, and I don't know what I did to cause it."
The Riverside County Sheriff's Department said the two men were gone by the time they arrived. They are continuing to investigate the incident.
Kang played with a security detail following her on Sunday and climbed into a tie for 26th courtesy of an impressive round featuring six birdies.
"I just kind of put it behind me," she said.
Brittany Lincicome edged out Stacy Lewis in a play-off to win the tournament.