Gardaí expect that there could be further attempts to cause disruption on the second day of Britain's Queen Elizabeth II's visit to Ireland.
Around 30 supporters of the Republican party Éirígí protested over the presence of UDA members at today's wreath laying ceremony in Islandbridge.
The group who gathered at Kilmainham Gaol were prevented by gardaí from getting close to the memorial garden.
Gardaí say peaceful protests will be facilitated, but well back from the venues the Queen is due to visit.
They say that any breaches of the peace or violent demonstrations will be met with a robust response, with the public order unit on standby.
Last night, 20 men were charged with public order offences arising from the violence in Dublin city yesterday afternoon.
They were brought before a special night sitting of Cloverhill District Court last night.
Another person was released without charge having received an adult caution at Pearse Street Garda Station.
The Army Bomb Disposal Team was called to the scene of a suspicious device at a gararge on the Dublin side of Kill on the N7 at 6am this morning.
The device was a hoax and the area declared safe a short time later.
The Army Bomb Disposal Team was also called out last night and removed a suspicious package from Blessington Street in Dublin.
Gardaí described that device as an 'improvised firearm'.
