"We won't know the proper measure of this result for a couple of months," said Johnson.
"It was frustrating for us and there was some naivety on our part.
"We couldn't hold field position all day long, didn't have many attacking line-outs and Toulon didn't play rugby.
"I was falling asleep and it was hard to play against. But that's the way they play.
"But we have to work hard, be honest with ourselves and come back next week.
"It's a difficult pool but this result won't become clearer until a later date. We will take the one point away with us and move on."
The Ospreys welcome London Irish to the Liberty Stadium next weekend who beat double Heineken Cup champions Munster in the other opening Pool 3 game.