It comes amid the increasing spread of Covid-19 in the capital, with cases there soaring in recent days.
Yesterday, 102 additional cases of the virus were recorded, with no new deaths.
Dublin accounted for 56 of the cases, while Limerick has also become an area of concern for the National Public Health Emergency Team (NPHET).
Dr Glynn warned people from the two counties that the virus is in the community and the next week is crucial.
The next 7 days is really important. In particular, people in Dublin and Limerick need to assume that #COVID19 is circulating.
1. Reduce your social contacts
2. Take a step back and keep your distance from others
3. Do not drop your guard just because you know someone— Dr Ronan Glynn (@ronan_glynn) September 7, 2020
As of September 5th, there have been 13,812 cases of the virus recorded in Dublin, while Limerick has recorded 817, according to information from the Government's Covid-19 Data Hub.
Speaking at yesterday's Covid-19 press briefing, Dr Glynn said talking about another lockdown is not always helpful.
"The language of lockdown is really unhelpful. If we have to recommend additional measures, they will be measures to protect people."
"We still have control over this, we still have the power to change the trajectory of this," he said.
