Law enforcement officials are actively trying to track down the man who got clocked by Nikola Jokic's brother on Monday ... with cops hoping people come forward to help with its investigation into the incident.
TMZ Sports has learned -- Denver PD has seen the footage of Strahinja Jokic punching a spectator in the stands after the Nuggets' Game 2 win over the Lakers on Monday ... but as of right now, no one has filed a report claiming to be a victim.