Two men was arrested at the Green Pride “protestival” in Preston Park, Brighton, yesterday (Saturday 20 July), Sussex Police said.
Officers confiscated cannabis from about 30 people, the force added, and referred five teenagers to the Youth Outreach Service and contacted their parents.
One man was arrested on suspicion of having cannabis with intent to supply and one man was arrested on suspicion of having cannabis.
Yesterday evening both were in custody after an event described by police as “well mannered and good spirited”.
The force said: “Sussex Police attended the Green Pride protestival in Brighton which concluded with minimal disruption.
“The force had a noticeable presence at the event, held at Preston Park, due to the large number of people anticipated to attend.
“Working in conjunction with Brighton and Hove City Council, officers engaged with participants early on to ensure the boundaries were clear and that people were aware of the legislation around cannabis.”
Many smoked cannabis openly at the event although just two men were arrested.
Chief Inspector Chris Veale said: “We were able to actively engage with a number of groups, clubs and individuals associated with Green Pride, many of whom had travelled from across the UK.
“This enabled us to set the tone early and give people the opportunity to make the right decision based on the information provided.
“We made it clear that we would facilitate lawful protest. However, we were also there to safeguard the public, particularly young people and children, and to enforce the law – and most people responded positively to our engagement.
“There was a calm community feel throughout the day, and the vast majority of those in attendance were well mannered and good spirited.
“The peaceful crowd was reflected by the low level of law enforcement.”