Speaking at the Scottish Government's coronavirus briefing, the First Minister addressed scenes at Kelvingrove Park in Glasgow on Thursday night, when police were forced to clear the park and two people were arrested.
"While I understand - and I really, really do - people's desire to enjoy the sunshine on the very few days a year we have any, please avoid crowded places," she said.
"This virus will take those opportunities if we give them to it, so we mustn't provide them."
The First Minister also asked that people who spend time outside take their litter away with them or dispose of it responsibly.
She said: "Refuse collectors across the country are doing an incredible job and I do want to thank them today - but they simply should not be having to clean up after mass gatherings."
It comes as Ms Sturgeon confirmed that Scotland had no new deaths from coronavirus in the last 24 hours.
She said this is the first time it has happened on a weekday since before lockdown and means deaths under this measure remain at 2,842.
Recording no deaths on a weekday was significant, she explained, because that had only previously been recorded around the weekend when registration figures tend to be artificially low.
Announcing new advice from the Scottish government on shopping, Ms Sturgeon stressed that everyone in Scotland has a duty to ensure the safety of the public and staff when non-essential retail shops open on Monday.
The guidance urged Scots to shop locally - within five miles of their home - shop alone or in as small a group as possible and to choose to visit shops outside of peak times.
Ms Sturgeon "strongly advised" shoppers wear face coverings to protect others - as she did on a visit to a New Look store on Friday - but she stopped short of making the practice mandatory.
She told shoppers to remain "patient and polite", adding: "These rules are there for the protection of all of us.
"Abusing retail staff because they're telling you something that you don't want to do is not acceptable.
"These people are at work and have to be kept safe too so please treat them with respect and courtesy."
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