Celtic could not find a way to break down Hearts at the weekend and drew 0-0.
The Bhoys were unable to beat Hearts due to their profligacy in front of goal, with Griffiths particularly guilty of wasting good opportunities.
It was an uncharacteristically poor performance from the striker, and Deila admitted that the 25-year-old should have got his name on the scoresheet.
“When you see those chances again, as a striker you can’t get clearer ones," the Celtic boss said to the Daily Record.
“Leigh has had four or five alone but he has scored in every game over a long period. Everyone has ups and downs over a season but I’m sure he’s irritated that he didn’t score."
Griffiths has been one of the players at Parkhead who has improved the most since Deila's arrival, and he is now established as the first-choice striker for the Bhoys.
The former Wolverhampton Wanderers man has scored eight goals in 16 games this term, and arguably been Celtic's best player.
However, his display against Hearts fell a long way below the high standards that he has set himself, and he will have to improve considerably if he is to keep his place.
Celtic are looking at bringing in another front-man, and they have been linked with Carlton Cole in the Daily Record in recent times.