A 14-year-old boy has been arrested after a tree was set alight in the garden of a family home in Hemlington.
Police were called to Dallas Court about 6:25pm on Tuesday 13 September.
The family was inside the home at the time, although they were able to escape unharmed.
Damage was caused to guttering and a window due to the heat, but officers said the damage could have been much worse if fire had spread to the nearby house.
A 14-year-old boy arrested in connection with the incident has been released on police bail while investigations continue.
Sergeant Paul Forbes said: “This was a dangerous incident which could have easily resulted in serious injury, or even fatalities, had the fire spread to the house.
"Our enquiries are ongoing and we currently have a teenager arrested. We would encourage anyone with information to call us or pass information anonymously via Crimestoppers.”
Middlesbrough Mayor Andy Preston said: “Decent law-abiding people have an absolute right to protection from this sort of behaviour that blights communities and puts lives at risk.
“Council street wardens were able to act quickly on Tuesday and their actions helped make sure this incident didn’t have even worse consequences. Our wardens are doing a fantastic job in partnership with Cleveland Police and the Fire Brigade.
“But they need the help of local residents to help them identify the tiny minority responsible for this behaviour and bring them to justice.”
Anyone with information is urged to get in touch with Cleveland Police on 101, quoting incident number 164592.