The Pars have spent most of the season languishing at the wrong end of the table and Jefferies believes changing the mindset of the players he has inherited is his first task ahead of Saturday's clash with St Mirren.
He said: "That's one of the reasons I've been given the job, the experience I've got in dealing with players. It's about making them believe that they can stay up. Talking to them, they seem a decent bunch."
He added: "It's major cup finals they've got between now and the end of the season.
"They are playing for themselves and for their own futures.
"That's football but we will help them all we can and try to give them the confidence to do that."
Bottom side Dunfermline are four points adrift of nearest rivals Hibernian and Jefferies added: "I know it's going to be tough and it's going to be tough for clubs above us as well.
"But I wouldn't have taken the job if I didn't think there was a chance. It would have been pretty pointless.
"We want to try. Things can change very quickly. There are enough games and enough points."