The cut means the wind farm will now have a maximum capacity of 400MW, which would require the use of 5MW turbines.
The project's site had been expanded to 19 square kilometres to allow a greater flexibility in the siting of the turbines. A spokesman for the Crown Estate, which manages the UK's seabed, said: "The Dudgeon site consists of mobile sand waves and chalk seabed, both of which create engineering challenges in securing the turbine foundations."
The Crown Estate is now to enter into negotiations with Dudgeon Offshore Wind regarding the granting of further rights over the Dudgeon project.
Planned for a site off Norfolk's north-east coast, Statoil and Statkraft acquired the project from Warwick Energy in October 2012. The proposed further rights would extend the existing arrangements, allowing Dudgeon Offshore Wind Ltd to call for a lease of the site.
The proposed wind farm area would be increased by up to 19 square kilometres, while the capacity would be cut from 560MW to no more than 400MW.
Further rights would be granted by way of a variation to the existing agreement for lease between Dudgeon Offshore Wind Ltd and the Crown Estate. It is expected that any such rights granted will expire on 28 February 2015.
The project was bought by Norwegian energy companies Statoil and Statkraft in October 2012.