The futures of a number of Fulham players have been the subject of speculation in recent weeks as the club battles to stay up.
German defender Riether still has over a year to run on his contract at Craven Cottage, but he has refused to give assurances over his long-term future.
"I don't think we should speak about the future, we have six games left and we believe we can stay in the league," Riether told the Fulham Chronicle.
Meanwhile, Moussa Dembele has admitted he had mixed feelings after making his full debut for the club in the 3-1 defeat to Everton.
The 17-year-old started up front for Felix Magath's side, but could not prevent Fulham from going down to another defeat to leave them five points adrift of safety with just six games left in the campaign.
Dembele, who came close to scoring in the first half when his header was saved by Tim Howard, insists Fulham must now dust themselves down and get ready for this weekend's clash with Aston Villa.
"If I had scored it could have been a different game," he admitted. "But I didn't so we had to try to keep our heads up and give it another go. I'm not pleased with my performance because we lost the game and it's always good to win.
"But, of course, to play was good for me. I was feeling a bit nervous before the match but it's a game of football so I just tried to enjoy myself and work hard for the team and for the club."
"It could be different but the game is finished now. Yes, it was unlucky for us but we have to move on and keep our head up for the next game.
"It is a big one at Villa and we have to make sure that we're ready for this game."