The coach used by Solihull Moors was "significantly damaged" as it left Bolton Wanderers following an FA Cup tie, the League One side has confirmed.
Wanderers said the Moors' vehicle was damaged in "an incident" after the team's 4-0 defeat at the Toughsheet Community Stadium on Saturday.
A representative said the damage occurred between 17:00 and 17:20 GMT.
They added that they were working with Greater Manchester Police to establish what happened and find those involved.
The club has urged anyone who witnessed what caused the damage to get in touch.
The police force has been contacted for comment.
The Wanderers representative also warned those attending Saturday's home tie against Blackpool in League One, which falls on Remembrance Day, to act respectfully and appropriately, as the club would "continue to take a zero-tolerance approach to all forms of anti-social behaviour".
Chief executive Neil Hart said any supporters who witness such behaviour should report it via "the dedicated One Wanderers phone number and safety officer email".
He added that having the support of fans "throughout the stadium" was "critical in helping us to put a stop to behaviour that does not represent the values of our club".