Actress-model Melissa Faith Yeo Lay Hong called the police emergency hotline in May and used vulgar language when talking to the operator who took her call.
The court heard that she became unhappy when the operator, Mr Mohamad Faizan Mohamed Rais, 38, told her to calm down.
She responded by hurling a swear word at him.
In another incident, Yeo, 33, who also works as a property agent, made a lewd hand gesture and hurled an obscenity at an SMRT employee in November last year.
She was fined $5,000 yesterday after pleading guilty to two offences under the Protection from Harassment Act.
State Prosecuting Officer (SPO) Mohd Nasri Haron said that assistant station manager Victor Chuang Shi Chang, 63, was at the control station of Bishan MRT station on Nov 21 last year when Yeo approached Mr Chuang to ask about the past transactions on her ez-link card.
Mr Chuang then informed her of her last two transactions. When Yeo asked for more information, he directed her to a functioning general ticketing machine about 50m away. Yeo went towards it but returned soon after and told Mr Chuang off, accusing him of giving her wrong information.
She later asked him for a feedback form and he gave her one. After taking it, she flashed him an obscene hand gesture and hurled a vulgarity at him.
SPO Mohd Nasri said that Mr Mohamad Faizan was on duty on May 2 this year when he received a call from Yeo at around 6.30pm.
Yeo wanted to find out about a case of an assault earlier in the day in which she was the victim. During the conversation, she also used an obscene word to refer to an investigation officer handling the case.
The outcome of the assault case was not mentioned in court.
Yeo was named one of FHM Singapore's 100 Sexiest Women in 2008 and 2009. In 2014, she appeared in a local movie titled Afterimages.
For verbally abusing a public servant, she could have been jailed for up to a year and fined up to $5,000.