Sunday's 4-2 home defeat to Manchester United has left Leeds in 15th position, five points above the relegation zone.
With sides below them having games in hand coupled with injuries to key players including Patrick Bamford and Kalvin Phillips, things are starting to look perilous for Leeds United.
The Whites face Liverpool and Tottenham Hotspurs in their next two games.
"It is impossible not to be worried," Bielsa told Sky Sports. "We have conceded 50 goals. Do you think I cannot be worried? How can I not feel responsible?
"We have to defend better. We are missing Kalvin Phillips and Robin Koch was substituted and we could not count on Pascal [Struijk] in midfield because he went back into defence.
"Not being able to come with the three defensive midfielders we have, there is a weakness in the recovery of the ball.
"In the first half we started well and ended well but didn't manage to score. In the moments we lost dominance they scored.
"After we got back level we had the chance to go 3-2 up and straight away they went up and scored again.
"We played better trying to get back into the game than when we were trying to keep a result but something has repeated that is difficult to resolve."
