Charlie Austin bagged an unanswered brace to secure a crucial win for the R's in tonight's Premier League clash at Loftus Road.
Lambert told reporters after the game: "The two goals we conceded were really poor. Two shots on goal and two goals but we have to score.
"We need that finishing touch. Christian has just come back from a long lay-off, I could not fault the possession but you can have as much of the ball as you want but if you don't score you don't win.
"We didn't play particularly badly. Whatever is said in the dressing room stays there. They know my feelings on it and we will regroup and go again on Sunday."
Villa are currently 15th in the Premier League table, two points off the relegation zone.