Bus drivers say they will not take on or let off passengers at Busáras after dark unless security's improved there.
It follows an alleged assault on a Bus Éireann driver at the central bus station in Dublin the week before last.
The National Bus and Rail Union (NBRU) said members will refuse to pick up and drop off passengers after 8pm from September 16th if there's no action.
They're also warning they will take action sooner if there is another incident.
Dermot O'Leary from the NBRU said drivers have to make sure they are safe.
He argued: "There's been a number of assaults at Busáras over the last number of months.
"Our members are coming to us, saying this isn't industrial action but about health and safety."
Mr O'Leary added: "As far as our members are concerned, the company - which is Bus Éireann in this case - and indeed the Government have a duty of care to both [the drivers] and the people that they carry.
"Unless something gives in terms of ramping up security significantly, than our members have told us they won't be putting passengers on or off buses from 8pm."
Last month, members of the NBRU carried an emergency motion calling for the withdrawal of bus and rail services from "problem areas" in the weeks leading up to Halloween.
Delegates at their conference voted unanimously in favour of the proposal, due to increased levels of anti-social behaviour on public transport.
