Villaraigosa said he has done nothing wrong.
"I voluntarily gave the city Ethics Commission information regarding those tickets, and we stand by our position that we were acting in an official capacity," the mayor said.
City and state laws require the mayor and all politicians to report gifts they receive and from who.
Under the law, the value of tickets cannot exceed $420 from any one source each year, but if elected officials conduct official business or have a role at the event, then they are exempt.
The mayor's office said Villaraigosa has attended more than 80 events for free in the past five years, but would not say what the value is of those tickets.
Officials said all of the events were part of his official duty to represent the city.
Officials said they are waiting for the Ethics Commission probe to end to see if he has broken any laws.