Fredrik Bond exited the project over creative differences earlier this month. Najafi is said to be in discussions to direct the Millennium Films sequel action drama, reported Deadline.
The film will see the return of leading star Gerard Butler and Morgan Freeman.
'London Has Fallen' is slated for an October 2, 2015 release in the US with a UK release yet to be announced.
Najafi's directorial credits include 'Sebbe' and the TV series 'Banshee'.