Fox Sports' Jay Glazer tweeted out video of the play, on which Coffman ventures well beyond the thick white sideline stripe separating the field of play from the bench, then basically tackles the unidentified assistant coach.
The NFL confirmed the fine to ESPN.com.
Titans coach Ken Whisenhunt didn't immediately respond to a request for comment.
The $30,000 fine accounts for nearly 5 percent of the $601,000 Coffman's slated to make this season.
Coffman could work as the Titans' No. 1 option at the position Monday night against Pittsburgh if Delanie Walker isn't cleared to return from a concussion.