Roxanne Beaven, 24, said an off-duty police officer tried to wrestle her to the ground, bruising her arm, after she told him to 'f*** off'.
The officer had tackled her after he heard her use the word 'c***' as he dropped off his own children at Gray's Farm Primary Academy, Orpington, Kent.
Mother-of-three Roxanne, who was with her two-year-old twin sons Archie and George, said she didn't believe the man was a police officer when he told her off for swearing as she chatted with other mums.
She said: "I admittedly told him to f*** off at first because I didn't know him from Adam.
"He has bruised my arm. It's disgusting what he has done to me. It's so sore, it really hurts. I ran into the school and burst out crying."
Roxanne, from Orpington, who also has a five-year-old son, has made a formal complaint against the officer.
She added: "I know I shouldn't have been using that language outside the school but the way he reacted was out of order.
"The word was used in conversation. It was not directed at him. He was off-duty. To me, that is a parent attacking another parent."
Met Police officers were eventually called to the school at 9am and Roxanne was arrested for a public order offence.
A 45-year-old woman who tried to pull the police officer away and knocked off his glasses was arrested for common assault.
Both were taken to a south London police station and issued with a caution after admitting the offences.
Another mum Dawn Cleary, 37, who was talking to Roxanne, said: "Everyone swears. All he had to do was say, 'Tone your language down a little bit.' It just went from one extreme to another.
"It was really horrible to stand there and watch. He blew it completely out of proportion."
Mum-of-two Catherine Oates, 30, also saw the commotion.
The 30-year-old said: "Roxanne's twin boys started screaming their heads off. We had no way of knowing he was really a police officer. I was disgusted."
An Essex Police spokesman said: "We can confirm we have received a complaint about an officer and as this matter is being investigated we cannot comment further at this stage."
Gray's Farm Primary Academy hasn't commented.
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