The FA have launched an investigation after referee Chris Sarginson twice had to stop the game, when Boro goalkeeper Jason Steele and the assistant referee were the target of bottles and other objects thrown from the crowd.
In a joint-statement, Lions chairman John Berylson and fan director Peter Garston said: "On Saturday, a wonderful game of football at The Den was overshadowed by the actions of a handful of mindless idiots who threw bottles onto the pitch.
"The FA, as they are duty bound to do, are investigating the events of Saturday. We, the football club, are working with police to identify and prosecute the perpetrators.
"Arrests have already been made, and we anticipate there will be more to follow. Those found guilty of throwing objects will be banned from Millwall for life.
"We pride ourselves in the passion of our support and the atmosphere created at our ground. But there are boundaries which cannot and must not be overstepped."
Source: PA
Source: PA