Eight members of the All-Ireland champions' panel were photographed taking part in an early morning training session in late March.
Dublin will be without their manager Dessie Farrell for the National Football League, he's serving a 12-week suspension for the breach.
Dean Rock sorry for Dublin breach, but stresses training session was one-off https://t.co/1ux9A9eUYx
— Irish Examiner (@irishexaminer) May 13, 2021
Rock says they've "learned lessons" from the incident and that it was a "regrettable decision to break the rules during the level-five lockdown.
Dublin get their Allianz NFL Division 1 campaign underway on Sunday 23rd of May against Kerry in Semple Stadium, Thurles.