The three people, all of whom are foreign nationals were charged after attempting to procure coins from passers-by in the Danish capital, reports the Ritzau news agency.
None of the three were present at the hearing, where police officers described the incidents that led to the charges, according to the report.
“She said ‘money' and ‘food' right in my face. I then produced my police badge,” one of the police assistants, who was in civilian clothes when approached by the beggars, said.
The officer had been sent out undercover with the aim of finding beggars breaking the law, writes Ritzau.
One of the three beggars, a 43-year-old Romanian, was photographed by the police officers begging near Nørrebro Station.
“There can be no doubt about what she was doing. It was her intention to be given charity,” senior prosecutor Marlene Beynon said.
One of the conditions for sentencing under the law is that it creates inconvenience for members of the public.
The second of the three cases was related to a man who was observed begging from a bench near Nørreport Station, while the third was near Dybbølsbro Station.
The second beggar asked the plain clothes policeman who arrested him for money, the court heard.
Defence lawyer Lene Sejersen was not about to speak with her three clients prior to the trial, according to the report.
Five people have now been convicted of begging in Copenhagen during the last 14 days.
The tough new Danish line on begging is a response to an acute problem in the city, according to Justice Minister Søren Pape Poulsen.
According to the new rules, a person can be prosecuted for begging without prior warning.
Up to 14 days' imprisonment can be given for begging on pedestrianised streets, near rail stations or on public transport.
A total of 43 people were given sentences for begging from 2012-2016, according to a Jyllands-Posten report.