Foley, 64, and another man, 37, were being held at Store Street Garda Station.
They were arrested at around 1pm when the city centre mall, off Talbot St, was packed with shoppers.
Gardaí were called after a dispute arose over the return of property between Foley and a business in the centre.
Foley, who recently operated a debt collection agency, has survived a series of attempts on his life, and has convictions for assault, robbery, and possession of weapons
The 37-year-old man is a cage fighter and is believed to operate a car dealership.