They say this would lead to better and safer access to the drug.
The demonstration is taking place at Mardyke Walk at 2 o'clock this afternoon.
Organiser Martin Condon says cannabis should not be illegal - and is urging the government to take action:
"The current prohibition of cannabis has failed in its objective. Kids as young as 12 are selling and buying cannabis on the streets of Ireland, and even on the Snapchat and Instagram kind of apps. So, the regulation of drugs is known to be a better avenue, way forward."
