The board on Monday (local time) upheld a decision by South African Justice Minister Michael Masutha, who intervened in plans for Pistorius' release to say the law requires the athlete to serve a sixth of his sentence before parole can be considered.
Pistorius was due to be released into house arrest in August after serving 10 months of a five-year sentence. His parole hearing was conducted before he had served six months.
"We are considering our position," Pistorius' solicitor Brian Webber told Reuters when asked if they would appeal the decision.
The family of the Paralympic gold medallist, whose lower legs were amputated as a baby, said in a statement on Tuesday that they were "concerned about the legality" of the parole decision and believed Pistorius was being unfairly treated.
"This experience leaves us with the uncomfortable conclusion that the public, political and media hype that was allowed to develop around Oscar's trial has undermined his right to be treated like any other prisoner," the statement said.
Pistorius was found guilty in September 2014 of culpable homicide, the equivalent of manslaughter, after he fired four 9mm shots through a locked toilet door on February 14, 2013, killing model and law graduate Steenkamp.
At a globally televised trial, he argued that he had mistaken Steenkamp for a burglar.
Prosecutors are appealing the verdict, arguing it should be murder because Pistorius must have known that the person behind the door could be killed, regardless who it was. The appeal is due to be heard on November 3.
A panel of five judges will hear the appeal. The judges could either reject the prosecution's appeal, order a retrial or convict Pistorius of murder themselves, legal experts say.
