The accident happened on developer St George’s Dickens Yard site on Ealing Broadway.
The crane operator was treated for shock but there were otherwise no injuries.
Emergency services were called to the site at 3.30pm.
A spokesman for St George, which is part of the Berkeley Group, said: “There was an incident this afternoon involving a crane at the Dickens Yard development in Ealing. No one was injured in the incident. The company is investigating the matter but cannot speculate as to the cause at this stage.”