The Hoops were already two goals up thanks to Dedryck Boyata and Stefan Johansen when they were awarded a penalty with 12 minutes remaining.
The Norwegian midfielder, who was felled in the box, grabbed the ball to take the spot kick but second-half substitute Griffiths, who is the nominated penalty taker, grabbed the ball from him before having his shot saved by former Motherwell goalkeeper Gunnar Nielsen.
It brought back memories of Celtic’s Scottish League Cup final win against Dundee United at Hampden in March when James Forrest and John Guidetti argued over a penalty before the former’s spot-kick was easily saved by United keeper Radoslaw Cierzniak.
The Celtic boss said: “It should be very clear – it is Leigh Griffiths that takes the penalties. So that is something we have to get out of the way. We can’t have it like this.
“That is hopefully the last time that we see that because it is nothing about being professional and being a team, because we shouldn’t fight about a penalty.
“It is very clear who is going to take the penalty and that is the way it is going to be in the future. The taker gets extra pressure and everyone knows that when you have a penalty, the longer you wait, the chances to miss get bigger.
“I don’t know (why Johansen did it), I haven’t asked him but 3-0 is a much different result than 2-0.
“But 2-0 is a good result. We had chances to win more but we were not more effective enough.
“I am disappointed that we didn’t score goals but good that we had a clean sheet and we have a very good chance to make the next stage. They had one or two chances so it was good that they didn’t score so I am happy but not very excited.”
Deila revealed that Gary Mackay-Steven injured his groin in the warm-up, which led to him being replaced by Forrest, but should be okay for the second-leg in Iceland next week, where Stjarnan boss Runar Pall Sigmundsson remains confident of turning the result around.
He said: “I am very proud of my team, it was a very good performance and a great defensive display.
“We could have scored an away goal, we had the chance and we were unlucky so I am disappointed. And I was disappointed that we lost a goal just before half-time.
“But I believe we can get a good result at home, I am confident. We have one game left.”