Sources have revealed that gangsters broke into the two properties and caused thousands of euro worth of damage.
The development has led to increased fears of a major escalation of the feud between Mr Big's drugs mob and dissident Republicans.
"The fellas broke into the houses and completely wrecked them -- it seems the criminals were trying to make a statement to what's left of Ryan's RIRA faction.
"They are challenging the dissidents -- trying to make the point that they are the top dogs in the feud. It is a very worrying development," a source said.
The Herald revealed yesterday that 'Mr Big' returned to Dublin last week and was arrested by gardai after they found balaclavas and cable ties in a car that he was travelling in at the south inner city.
The attacks on the two homes happened after the crimelord's return from Spain, where he has been based since September's murder of Alan Ryan.
The properties that were attacked are located on Dublin's northside. The occupier of one of the houses is a well-known sportsman.
A source said: "Both of these individuals would have been close to Alan Ryan but not necessarily involved in any form of terrorist activity."
The return of Mr Big -- who is understood to be hiding out in hotels and staying with pals -- has heightened tensions in the criminal underworld after last week's killing of crime godfather Eamon Kelly.
'Mr Big', considered one of Ireland's biggest drug traffickers, is suspected of organising Alan Ryan's murder with a close associate who is on the run from gardai after a warrant was issued for his arrest last week.
This older criminal is a Tiger kidnap mastermind who has been striking fear into the criminal underworld for years.
Gardai have carried out a number of searches in Cavan and Dublin over the past week to try and locate the veteran criminal who is facing serious charges in the courts.
'Mr Big' was stopped by officers from Kevin Street Garda Station in the south inner city during a routine traffic stop on Tuesday night of last week.
The feared crimelord was in the company of a notorious hood when detectives pulled over the car in the Marrowbone Lane area. Cable ties and balaclavas were discovered.
'Mr Big' and his drug-dealing pal were questioned but released the same night.