A two-year-old boy was repeatedly spat at, threatened and racially abused, his mother said.
Yasmin Johal was walking in Mansfield Road, Nottingham, with her son Remy and boyfriend Danny on Sunday afternoon when a man followed the young family.
The 23-year-old said the man spat at her son "multiple times", racially abused him and threatened to "smash his head on the pavement".
A tweet about the abuse has gone viral, and police are investigating.
Ms Johal told the BBC the man followed her while she was pushing her son in a pushchair.
She said he then repeatedly spat at the pushchair, and used a racial slur at her son.
Her boyfriend then turned around and asked the man what the issue was, and he said: "Your child is my problem."
She said: "He made it very clear within the first few things he said that his problem was with Remy, which was really scary.
"If it was just directed at me I wouldn't really be fussed, but it was a massive shock."
The vlogger's tweet about what happened has attracted a number of messages of support.
The Coventry-born mother - whose family is of Indian heritage - moved to the Sherwood area of Nottingham six months ago with her young family.
She said she had another person shout racial abuse at her while shopping two months ago.
In light of the latest incident, she said she wanted to move away.
"It's amazing to see all the messages of support from people online, but that's online," she said. "We don't feel safe here anymore."
Supt Matthew McFarlane, from Nottinghamshire Police, said racially-aggravated public order offences "are not acceptable" and officers were now working to track down the individual.
He added: "This is an awful incident, I fail to comprehend how anyone can abuse and spit at a child like this.
"Racist incidents will not be tolerated."
The force has described the suspect as white, bald, wearing a khaki baseball cap, a green and brown jacket, blue jeans, and a black backpack.