Johnson returned figures of 12/127, but Smith played down the underperformance of his batsmen at SuperSport Park in Centurion on Saturday.
South Africa made 206 in their first innings and 200 in their second, as only AB de Villiers (91 and 48) was able to progress past 35 in two attempts.
“I believe he [Johnson] is bowling well, the wicket played a big role in the success that he had,” Smith said after the match.
“The stats in the Ashes also say he picked up a lot of lower-order wickets, so the key is for our top order to set some big partnerships.
“Hopefully, we make sure he keeps coming back and bowling and bowling and bowling.”
Without the efforts of De Villiers, the top six Proteas scored 57 runs in the first innings and 68 in the second. Smith, however, said there was nothing wrong with the gameplan of his batsman.
“I think our gameplans and mindsets are good. I think the surface suited his style of bowling here.
“He got a lot of indifferent bounce. He got a lot of balls to get really big on batters from good areas, which made it very tough.”
Smith said it was not long ago that the Proteas were able to put Johnson under pressure.
“He’s obviously in form at the moment and confident. We’ve just got to find a way to make sure he doesn’t bowl as he did in this game.”
Smith said everything went wrong for the Proteas during the match.
“We just never hit our straps in any department throughout the four days. Three of the four days we had little mishaps with illness, injury, niggle and everything just seemed to not fall into line,” he said.
“Ultimately, we allowed Australia to play cricket on the front foot. When they do that, they’re a very dominant team, no matter what Aussie team it is. We need to look at ourselves.”
He said that at 100 for four in the first innings the Proteas had a real opportunity.
“We weren’t able to take that. From then on in, we were under pressure.”