Beroe Stara finished with eight men after two players were sent off for fighting with each other during half-time before beating Neftohimik Burgas 2-0 to move up to fifth in the Bulgarian league.
"I've never seen anything like this," Beroe coach Petar Hubchev said.
"I was not in the tunnel at the time of the incident and firstly, I would like to talk to people who created this nonsense," added former defender Hubchev, who was in the Bulgaria team that reached the 1994 World Cup semi-finals.
Beroe were reduced to eight men when Brazilian midfielder Elias received a second bookable offence for diving midway through the second half but the Stara Zagora-based side held their two-goal lead from the first half.
Beroe, the 1986 Bulgarian champions, competed in this season's Europa League qualifying rounds after winning the national cup in May.
Pirin Gotse Delchev goalkeeper Abdi Abdikov was sent off for hitting a team-mate during his club's 5-1 loss at Cherno More Varna in the Bulgarian league in April. Abdikov was banned for four matches.