London police carried out a controlled explosion on June 7.
They were investigating two suspicious vehicles found unattended near the new U.S. Embassy.
The area was cordoned off, and a bomb disposal robot was dispatched. Specialist officers were in the area.
Police later said the vehicles were deemed not suspicious. Roads are expected to reopen shortly.
Security has been heightened in London since the city was hit with three terrorist attacks in three months. In the most recent attack, on June 3, three Islamic extremists ran pedestrians over with a van on London Bridge and stabbed people at a local market. Eight people were killed and 48 were injured.
