Foster was already under pressure, having been on the receiving end of criticism from fans for misses in the matches against Panama in March, and the penalty miss will have done nothing to improve that.
But there are extenuating circumstances, according to Broos, who is likely to make Foster his lead striker at the World Cup, with Evidence Makgopa and Iqraam Rayners the other two players in the squad capable of playing in that position.
"You have to remember that Lyle didn’t play in three of the last four matches for Burnley since they changed the coach," Broos said.
"He wasn’t even on the bench anymore. I think that Lyle needs a little bit of confidence from our side, and also a little bit better physical condition. A good Lyle is quick and active.
"We didn’t see much of that Lyle in the first half (against Nicaragua). But that’s not the reason why we changed him. That was the plan even before the game, that Lyle would play the first half and Iqraam would play in the second half."
Foster has 10 goals in 31 caps for Bafana Bafana, but has scored only once in his last six appearances.
"Lyle, at the moment, doesn’t have a lot of confidence. He doubts himself a little bit. So we have to work on it in the coming days and train to make sure that he is at the level he was a few months ago," Broos said.
"Those things happen. You change coaches and suddenly they put you on the bench, followed by the stands.
"He is struggling a little bit right now. But we will be okay. We have time to put him back where we want him."
South Africa take on co-hosts Mexico in the World Cup opener in Mexico City on June 11, before a clash with the Czech Republic in Atlanta on June 18 and a final Group A fixture against South Korea six days later in Monterrey.