Sickos launched a firework from a car into a pram and set a baby’s clothes on fire.
Police have launched a manhunt after the incident at the junction of High Street South and Periwinkle Lane in Dunstable, Bedfordshire, around 9am on November 6.
Officers do not believe the child was targeted, and they escaped unharmed.
PC Sam Allen, of Bedfordshire Police, said: “It was a very distressing incident and could have resulted in serious harm.
“We are very keen to speak to anyone who has information or was in the area at the time and has dashcam footage that could assist our enquiries.”
Anyone with information call 101 or visit the force’s online reporting tool and quote reference 40/60291/20.
Earlier this month, a cat tragically died after a firework was attached to it and set alight.
The sick abuse was carried out in Rotherham, South Yorkshire, a few days before Bonfire Night on November 2.
In the aftermath, the RSPCA called for stricter controls on the sale of use and fireworks, The Star reported.
It wants their use to be restricted to November 5, New Year's Eve, Chinese New Year and Diwali.
A spokesperson for the charity said: "We were contacted on November 2 after a cat was killed in Rotherham, South Yorkshire when a firework was attached to him and lit.
"On Bonfire Night itself, we were made aware of two incidents – one in Bradford, West Yorkshire, and one in Kenilworth, Warwickshire – in which fireworks had been strapped to kittens before being set off.
"And on Friday, November 6, the burned body of a cat was found strapped to a firework in Queensferry, Wales."