From Politico:

The Los Angeles mayor gave a pretty obviously nonresponsive answer when Radio Iowa's O. Kay Henderson asked if he has any presidential ambitions for 2016: 

Villaraigosa spoke with Radio Iowa before his speech this evening. As for whether Villaraigosa might run for president in 2016, Villaraigosa said he plans to “reflect” when his term as mayor ends in the middle of next year before deciding what he’ll do next. “I want to figure out how we move America and, importantly, my state, toward what I call a radical middle,” he said.

He was in Iowa to headline the state Democratic Party's Jefferson-Jackson Dinner, which is of course what you do if you are simply interested in promoting policies of the "radical middle." 

Villaraigosa has talked about running for governor of California in the past, so it's no shock that he has ambitions beyond his city and perhaps state. That he (as well as other mayors like Cory Booker and Rahm Emanuel) are already being talked about as presidential prospects for next cycle reflects both the prominence of mayors in the Democratic Party, and the relatively thin collection of governors and senators the party might field in 2016 if Hillary Clinton doesn't run.

The Democrats actually still have a number of white male governors with executive experience and track records of appealing to state-wide electorates who sound far more plausibly Presidential than these guys. But the Democratic Party is evolving along with the demographics of America, so, yeah, sure, why not Tony Villaraigosa in 2016?