City workers took photos of the damaged glass on the Leadenhall Building after the incident on Tuesday.
Multiplex is main contractor on the 22 Bishopsgate site which will be home to a 62-storey tower.
Multiplex said: “On 1 August a tower crane working on the 22 Bishopsgate site was lifting a steel beam, which damaged a small part of the external glazing of The Leadenhall Building.
“No one was injured in the incident.
“The process to replace the damaged pain of glass is underway.”
A statement from client AXA IM – Real Assets said: “Multiplex, our main contractor at 22 Bishopsgate has informed us that on 1 August a tower crane working on site was lifting a steel beam which damaged a small part of the external glazing of the Leadenhall Building.
“The building is safe, there were no injuries and work is underway to replace the damaged section.”
Picture courtesy of Twitter/@cameronfalconer