Robinson saw his team give the Springboks a helping hand by gifting them points, particularly when Mike Blair's wayward pass allowed Adrian Strauss to score his second try of the afternoon.
"We've got a lot to learn," Robinson said on BBC1. "A lot to learn in improving defence and also in attack, particularly physically.
"I felt they bullied us a little in the first half."
Robinson now wants to see a reaction to the result, and last week's more punishing loss to New Zealand.
"Next week against Tonga we need a performance there to put together the lessons they've learned from the first two games," Robinson said.
"There's a lot for us to look at. The disappointing thing from our side is we allowed a side to get a lead again and that's something you can't afford to do."
Scotland were chasing the game in the latter stages, but had plenty of possession and Robinson felt the match could have turned in his side's favour.
"But I thought South Africa defended superbly well," he said. "If they hadn't defended as well as they had, it could have been a different story."
He rued the penalties his side conceded in the first half and was regretful over South Africa's tries, saying the first for Strauss following a maul made him "very, very angry".
"They didn't have to do a lot to win the game because we gave them field position from penalties," Robinson said.
South Africa head coach Heyneke Meyer agreed his defence held the key in the end.
"All credit to Scotland, they played superbly and just great, great defence kept them out," he said. "It was not a great game but I'll take an ugly win.
"We know we can play much better but we mustn't take anything away from Scotland.
"They came out and gave everything for their country. I think they can be proud of what they achieved today.
"We're in a learning curve and I thought the guys didn't panic. Our defence was awesome.
"To keep them out at the end, it really showed the character of this young team."
Man of the match Francois Louw added: "You've got to give credit to the Scots. They came out and put on a fight there. We had to fight for every inch.
"Credit to our guys for holding out in defence."
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