The explosion, which is created by filling a bottle with dry ice, occurred about 7 p.m. in a restroom at Terminal 2, which is home to several international and domestic airlines.
Police have made no arrests and the Los Angeles Police Department is now handling the investigation, said FBI spokeswoman Laura Eimiller.
Officials said an airport employee heard an explosion in a men's room and went to investigate. He discovered a 20-ounce plastic bottle that had contained the dry ice. The blast did no damage, and no injuries were reported.
Investigators combed through the restroom for evidence, authorities said.
In May, a dry ice bomb at Disneyland temporarily shut down Toontown.
After the explosion Sunday, operations were suspended in the terminal, and flights were delayed until about 8:45 p.m. as the LAPD bomb squad responded. Police estimated about four flights were affected.
Operations resumed afterward and no flights were reported as being delayed Monday because of the incident, according to the Federal Aviation Administration.
Last month, a former Transportation Security Administration worker was arrested after making threats against the agency and LAX terminals.