Dons fans Findlay Duncan and Nicholas Simmers pleaded guilty to possessing the devices when they appeared at Dundee Sheriff Court yesterday.
Sheriff Tom Hughes has banned them from attending games in Scotland ahead of their sentencing.
He said: "I don't think you appreciate how serious this is. The use of these is causing considerable panic in sports grounds in Scotland and it has to be stopped. They will almost inevitably attract custodial sentences.
He added: "This needs to be gotten rid of from Scottish football."
The pair had been among 3000 Dons fans at the 13,000 sell-out fixture at Tannadice Park in Dundee on Wednesday, which the visitors lost 2-1.
The court heard police had been called to a city bar after a smoke bomb was set off. They were led to Simmers, who was possessing smoke flares near the ground and handed them over.
Duncan was arrested in the stadium after several flares had been let off in the Aberdeen section of the ground.
Duncan, 21, of Inverurie, admitted to possession of a smoke grenade and Simmers, 29, of Aberdeen, two flares.
Simmers's lawyer said he had not realised the consequences of his actions.
Sentence was deferred until January 27 for background reports.