The pair were held alongside a 20-year-old American man after officers discovered 339 joints ready for sale at the underground club.
They were found hidden inside plastic bags and were labelled as either small, medium or large and were priced.
Police say the club, which has not yet been named, was being used as a front for drug dealing.
Officers also seized €2,245, credit card slips and weighing scales.
A police spokesman confirmed: “National Police have arrested three members of a cannabis club.
“The men – three men aged 20, 27 and 52 from the United States, Ireland and the United Kingdom, are suspected of selling drugs inside an underground establishment acting as the organisation HQ which was apparently functioning as a cover for drugs dealing.
“The investigation began after police received information about a property linked to an association backing the regularisation of cannabis which had no business licence and in which drugs were supposedly being sold.
“During the operation, officers seized different amounts of cannabis resin that customers are believed to have acquired on the premises.”
The spokesman added in a statement: “In the case of the joints, they were found inside plastic bags classified according to their size – small, medium and large – and their respective prices.
“During the search weighing scales and a dozen receipts pointing to payments made using bank cards inside the premises were also discovered.”