The 27-year-old, who was cleared of murder, killed the South African model by firing four gunshots through a toilet door at his home in Pretoria, South Africa in the early hours of Valentine's Day last year.
After court adjourned, Mike Steenkamp told The Telegraph: "I think the law has taken its course and the fact is that maybe there's room for the state to appeal.
When asked if he believed that Pistorius should have been found guilty of murder, Steenkamp said: "He is now a killer and you cannot lose that identity, it will be with him forever. No matter how you put it, it's something that will never go away.
"He didn't get off Scott free which would have been no justice at all. I think even if it's 10 months, he will be thinking about things and he will know somewhere along the line that he did something wrong."
Pistorius claimed that he mistook Steenkamp for an intruder when he fired the gun.