Glasgow Cannabis Social Club said yesterday's event was a "celebration" of the substance and had been organised to "enlighten members of the public".
Organisers said they had hoped 600 people would turn out. However, Police Scotland said that at its peak only about 150 people were in attendance.
The crowds were kept under the watchful eye of officers, who largely kept their distance but occasionally made unwelcome patrols through the masses. While many smoked cannabis openly, the police were not prepared to turn a blind eye in all cases.
A police spokeswoman said that, while there was no disorder and no arrests had been made, five males had been reported to the procurator-fiscal for alleged cannabis possession.
The force had faced criticism in the run-up to the event following allegations they were set to ignore illegal drug use at the festival.
Derek Anderson, who had travelled from Cumnock in Ayrshire and said he supported an overhaul of cannabis laws, was one of those interrupted.
"They've seen me smoking, and there was a bit of grass in front of me," he said. "They've come up, searched me and taken my details. Considering the day, and the fact that everyone's doing it, you don't expect them to single folk out. It's a peaceful event.
"They took a gram-and-a-half and said they were going to test it, so presumably they'll be back in touch. It's put a bit of a dampener on the day and it's not as if they haven't got anything better to do."
The event, which was beset by technical issues due to problems with power generators, included speeches and performances from comedians and bands. Many in attendance said they believed the tide was turning against criminalisation, following liberalisation of drugs laws in other countries.
Linda Hendry, spokeswoman for the legalise cannabis in Scotland campaign, said she had been lobbying for deregulation since 1979 and that she believed a Yes vote in September could be a catalyst for more liberal drug laws north of the Border, with classification currently decided at Westminster.
She said: "At the moment taxpayers' money is being wasted enforcing the illegality of something that's better than alcohol or tobacco."
"I would like to see it legalised in my lifetime. We've legalised gay marriage, and I can remember when gay acts were illegal."
Anne O'Neill was due to speak at the event about the medicinal benefits of cannabis. She said she had used the drug legally for 10 years while living in Oregon to help with chronic insomnia as part of a medicinal marijuana programme but had been "too afraid" to purchase it illegally in Britain.
"I've been suffering since I came to the UK in 2004," she said. "It helps with chronic pain, multiple sclerosis, anxiety, depression, pain from cancer and so many other things.
"I have had health scares as a result of the prescription drugs they've put me on instead. I'd like to see it legalised across the board and for it to be regulated and taxed. But if that's not possible at least get the sick people this medicine."
Robyn Brown, 23, from Hamilton in South Lanarkshire, said she had been using cannabis since she was 16. "It hasn't damaged me, it makes me feel happy," she said. "It should be legal, it's better than alcohol as you just chill out."
Organisers said they did not encourage cannabis use at the event and those who did choose to consume the drug did so at their own risk. Audience members were asked not to bring alcohol as it could give police an excuse to search them.
Scottish Conservative MSP John Lamont said that a "carnival in homage to an illegal substance" should not have been allowed. "It was inevitable that, in a festival of cannabis, there was going to be mass smoking which police couldn't control," he added. "It's remarkable it was ever given the green light to go ahead."