The European Monitoring Centre for Drugs and Drug Addiction said it did not envisage governments here following the move by the South American country.
Agency director Wolfgang Gotz said he did not “exclude” the possibility that other countries might follow suit in the future.
Uruguay legalised the sale and use of cannabis last December — becoming the first country in the world to do so, in defiance of UN laws.
The US states of Washington and Colorado have also legalised the cannabis trade.
Publishing the agency’s 2014 annual report, Mr Gotz said that Uruguay had approached it to join a scientific committee to monitor the operation and effects of legalisation.
“I don’t know if we can do it, because of resources pressure and manpower,” Mr Gotz said.
He said he did not envisage any country in Europe adopting the Uruguay model any time soon.
“As far as governments here I cannot see any impact. In civil society they are discussing this issue more intensively,” he said.
Mr Gotz said it was “too early” to say what the impact of the legalisation move will be. He said he did not “exclude” it as a model that other countries might follow, “not so much in the near future, but in the future”.
Paul Griffiths, a scientific director at the drugs agency, said it was impossible to say how long the scientific community would need to judge the impact, pointing to the lengthy time it took to assess the full damage of smoking.
Mr Griffiths said its annual report showed that increasing numbers of people were seeking treatment for cannabis use, and it was now the most common drug among new clients.
He pointed out that just under 1% of people who had taken cannabis were daily users.
The Health Research Board said the trend was similar in Ireland, with the number of daily users “well below 1%”. It said 46% of clients entering treatment for the first time identified cannabis as the main problem drug.
The agency report said that cannabis-related emergencies appeared to be a “growing problem”, often combined with alcohol intoxication.
Laurent Laniel of the drugs agency said the growth of large-scale domestic cannabis production had resulted in a rise in the potency of herbal cannabis, combined with a reduction in protective anti-psychotic properties commonly found in cannabis resin.
He said resin producers in Morocco had begun a “fight back” by growing stronger resin.
Mr Griffiths said the Moroccan producers were using genetically modified seeds to grow the more potent resin and that they were trying to “compete” with domestic European gangs.
He said organised criminal networks in Europe were “generating a lot of profit” from domestic cultivation, which required relatively low levels of investment and less risk of detection, compared to importation.