"We note that the case continues to grow in scope and we are glad that the police are now doing everything they can to get the facts on the table," NFF secretary general Kjetil Siem was quoted as saying on the NFF website.
"That is in the interests of football, regardless of what the conclusion will be. I would again remind you that no-one is convicted, although this development in the matter is very serious."
The arrests came as police continued investigations into the possibility that three matches outside of Norway's top flight had been rigged. Of the players arrested, three were from Follo FK club with the other representing Asker.
"We must let the police do their job and focus also on what we can do to help," NFF president Yngve Hallen told the FA's website.
"This evil shall not be allowed to destroy the football and sport."