Dejagah, who scored Fulham's goal in the 3-1 defeat to Everton last Sunday, said that the Whites must start taking more of the chances they create otherwise they will not be able to win at Villa Park.
"Of course, I was happy for the goal but for the team as well because we worked hard in the game," Dejagah told Fulham's official website. "But, if you see after the game, we have no points and that's why I was very, very angry afterwards.
"If you see the Everton game, we played very well and had a lot of chances, but you have to score goals. This is a problem in our team, we need to score goals.
"I think Saturday is a hard game because Aston Villa is the home team. They play very well in their home games – they beat Chelsea a couple of weeks ago – but this is football, we have to go there and take points. We need the points."
Fulham are five points from safety with just six games remaining.