No bomb was found aboard the Delta Air Lines Flight 110 from Atlanta, and after questioning by the FBI and airport police, federal investigators had decided not to pursue charges, FBI spokeswoman Laura Eimiller said.
She said they also concluded the man should undergo a psychological evaluation.
The plane was only minutes from landing at Los Angeles International Airport shortly before 10:30 a.m. Wednesday when the man "jumped up and started running ... (and) yelled 'I've got a bomb,'" passenger Bruce Worrilow told Fox 11 News.
Eimiller, who noted that the sequence of events was unclear, said the plane was a minute or two from touching down when the man apparently left his seat and walked to the rear of the plane, where he scuffled with a flight attendant.
After passengers restrained him, the man claimed to have a bomb, then later lunged for an exit door and assaulted a passenger, Eimiller said.
Passengers and flight crew members then restrained him a second time, binding him with plastic ties.
Eimiller said the man's identity had not been confirmed.
The man was expected to be turned over to Los Angeles police. Eimiller said he could face state charges.
The motive for the alleged threat was not immediately clear, Eimiller said.