Parts of what police described as an “extremely crude” device were taken away by police for further examination after an explosion in east Belfast on Wednesday night.
Officers said no one was in the Kenilworth Place property at the time of the incident and no one was injured.
First Minister Peter Robinson condemned those responsible.
“This incident and others, including a hoax device in Newtownabbey last night are attempts by a small minority to use fear and intimidation,” he said.
“Anyone who would place such a device outside a house clearly has no regard for human life. Thankfully no one was injured, but it causes great concern amongst people living in the area.
“There are a small number of people in our society who believe they can use violence or threat to drag Northern Ireland back to the past. People want to leave this behind and I know that the community stands united against those responsible.”
Army Technical Officers were sent to the scene, and police later confirmed the device is not thought to have been a pipe bomb.
A number of homes were evacuated during the security alert and a local community centre provided temporary accommodation until they were allowed to return to their homes after midnight.
Police said they are still investigating a motive and have appealed for information.