The motive was disclosed a day after the arrest of Dicarlo Bennett, a 28-year-old employee for the ground handling company Servisair.
"I think we can safely say he is not a terrorist or an organized crime boss. He did this for his own amusement," said Los Angeles police Deputy Chief Michael Downing, who heads the department's counter-terrorism and special operations bureau.
No one was hurt on Sunday when two plastic bottles packed with dry ice exploded in an employee bathroom and on the airport's tarmac. An unexploded device was found Monday night.
As a result of the incident, airport officials plan to meet with law enforcement authorities to examine potential security enhancements at one of the nation's busiest airports.
The meeting also will explore the handling and transport of dry ice and other hazardous materials and possible improvements to those procedures.
Arif Alikhan, deputy executive director for Homeland Security and Law Enforcement at Los Angeles World Airports, said such meetings are routine after problems.
"We'll look at all layers of security existing at the airport, including technology, physical infrastructure, the partnership of tenants, awareness of employees to potential hazardous items like dry ice," Alikhan said.
Workers at the airport must pass a criminal background check before they can get a security badge for access to restricted areas, LAX spokeswoman Nancy Castles said.
On Tuesday, police arrested Bennett, who was booked for possession of a destructive device near an aircraft and held on $1 million bail.
It was not immediately clear whether Bennett had a lawyer. A message left on a phone number listed at an address for Bennett was not returned.
Despite the arrest, travelers saw stepped-up security patrols at all terminals as well as the airfield, Los Angeles Airport Police spokeswoman Belinda Nettles said.
Dry ice is routinely used by aircraft catering companies and restaurants to keep perishable food safe.
Bennett took dry ice from a plane and placed a loaded bottle in an employee bathroom, according to a law enforcement official briefed on the investigation who wasn't authorized to speak publicly and asked to remain anonymous.
The commotion caused by the explosion delayed several flights. Remnants of another device were found the same night on a tarmac outside the main international terminal.
Police had pursued a theory that the bombs were placed by a disgruntled employee due to a labor dispute.
Servisair said in an emailed statement that it had no comment beyond confirming that Bennett was an employee of Servisair at the time of incident.
The bombs were made by putting dry ice in 20-ounce plastic bottles. When a bottle is capped, pressure builds up due to a chemical reaction and can cause an explosion.
The LAX explosions recalled a May incident at Disneyland, in which police said an employee placed dry ice-packed bottles in a food cart and trash can. Both exploded; no one was injured.