The US-born 25-year old, who commenced his career with Blackburn Rovers in 2004, is believed to be considering an offer from the New Zealand according to O Kosmos.
Johnson was a member of the Manchester United youth academy before moving to Blackburn where he gained his first team debut in 2004 and then experienced loan spells with Preston North End and Darlington.
He then moved permanently to Wolves in 2007 and had a brief stint with Leeds United before joining MK Dons in August 2007. He has been in Milton Keynes since then except for a spell with Stockport County earlier this year.
The reports also suggests that the Phoenix are also after Argentine playmaker Roberto Carlos Cornejo.