The man, described as middle-aged and wearing a suit, did not stop after hitting the youngster, despite screams from Lacie's terrified mother Serrena.
"Lacie didn't even see him coming," Serrena said.
"He glanced over and then carried on. She was lying on the floor at this point, bleeding.
"I was hysterical. I shouted after him, asking him to stop. He dawdled and then carried on. He didn't bat an eyelid."
With help from staff around Telford Town Park, the family, from Donnington, were able to get Lacie to hospital, where she was treated for a number of minor injuries.
"The doctor said if she had landed on her neck, it would have been catastrophic," Serrena said.
"I can't get into the mind of someone hitting a small girl and just riding off. She's not the biggest child in the world. She was just waiting there, stationary.
"The chap was going fast, we thought he was going to slow down but didn't make any attempt to slow down or move.
"I just want him found. He can't just hit a child and not even acknowledge that it happened."
Anybody with information is asked to call police on 101.
Alternatively, contact Crimestoppers anonymously on 0800 555 111 or at crimestoppers-uk.org