The president of Greek club PAOK has been banned for three years after storming onto the pitch with a holstered gun on his belt, league organisers said.
PAOK were also docked three points and fined, meaning they drop to third place in a tight championship race with AEK and Olympiakos.
The ruling, which also includes a 100,000-euro (£87,560) fine for Greek-Russian businessman Ivan Savvidis and a separate 63,000-euro (£55,150) fine for PAOK, is open to appeal.
Also on Thursday, the monitoring committee of FIFA recommended the immediate suspension of Greece's football federation, according to a letter leaked to Greek media.
The Greek league will resume on Saturday after being suspended on March 12 in the wake of the Savvidis incident.
The clubs have agreed to a list of government demands, including point deductions and automatic relegation for clubs responsible for violence.