Cops investigating Ian Ziering's crazy biker brawl are zeroing in on at least one of the bikers for vandalism charges ... and, as of now, they're not as concerned about the fight side of things.
Law enforcement tells TMZ ... the main focus of the case is a potential felony vandalism charge against the bikers for damaging Ian's car, but no arrests have been made yet.
We're told the new videos that emerged, in which Ian is seen initiating the violence by pushing one of the bikers, show this fight could be considered mutual combat. If that's the case, battery charges are unlikely, especially since none of the bikers have filed a police report.
Let's face it ... that wouldn't be a very biker gang thing to do.
Another reason they're not running to cops ... we're told the mini motorbikes they were riding are illegal to ride on public streets or freeways.
As for the vandalism -- one of the bikers is seen clearly on video using a helmet to smash Ian's windshield. When the case gets submitted, however, the L.A. District Attorney can add battery charges if they feel the evidence is there.
ICYMI, we spoke with 2 men who ride with the 605 Minibike Gang, which was spotted in the infamous New Year's Eve vid ... and they told us it was Ian who started the big brawl, not their crew.