England clung on to force a draw on the last day of the first Test in Centurion after they lost five wickets for 13 runs to end on 228 for nine in their second innings.
Smith said the opening Test had "raised some question marks" over England's line-up while South Africa coach Mickey Arthur singled out opener Alastair Cook and Ian Bell as being under extra scrutiny.
Strauss said it was foolish to make assumptions after one match.
"I am very comfortable with our middle-order. Matt Prior has scored a lot of runs for us in the last 12 months. Paul Collingwood is in great form and it was only two games ago that Ian Bell played a fantastic match at The Oval to help us win the Ashes," Strauss told a news conference on Thursday.
"If he (Smith) wants to base his judgements on one game, I would always shy away from that myself."
However, Strauss said that England have not ruled out making changes for the second Test, which starts at Kingsmead in Durban on Saturday.
"It is not definite that we will keep the same balance. It is an option but there would have to be reasonably strong reasons to change the balance at this stage but we certainly haven't ruled it out.
"The fundamentals are still the same in as much as you try and select the best XI to win you a test match and we need to think what that XI will be," Strauss said.
South Africa are expected to make one change with fast bowler Dale Steyn likely to be included after missing the first Test because of a tight hamstring.
"Dale is coming along nicely. He bowled 10 overs in the nets on Wednesday and there has been no comebacks on it," said Arthur.
"We are sure he will be fit and ready to take his place but we will wait until Christmas Day to make our final decision."
If Steyn does play then it is probable that paceman Friedel de Wet will be the player to miss out.
"Myself and Graeme have been very consistent in terms of our selections. If Dale is fit it could possibly be a straight swap for Friedel," he added.
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