France looked in peril of being pipped to top spot in Group D after a fine 40th-minute goal from Edin Dzeko gave Bosnia a 1-0 lead that their tenacious first-half performance at Stade de France richly merited.
The hosts managed to stem the tide in the second half, however, and a penalty by Samir Nasri with 12 minutes remaining gave them the point they needed to make sure of qualification.
"In the first 45 minutes, we didn't play," said Blanc. "At half-time we said that and asked the players where they wanted to go.
"If it was the play-offs, they just had to play as they had in the first half. We asked them to let go a bit and look after the ball better.
"We made lots of mistakes in the first half. In the first half we were transparent, but in the second half, the same players who were transparent in the first half played really well.
"We won't forget about the difference between the two halves but we'll also remember the fact that we came back and were able to qualify. The second half was as encouraging as the first half was disappointing.
"I'm pleased by the players' reaction. If there hadn't been one, we'd be sitting here (in the press conference) talking about the play-offs."
Blanc said he had been proud of the way his side pushed for victory in the game's dying stages, but he will nonetheless have been troubled by the fragility of their first-half showing.
France are expected to arrange two friendlies next month before taking on Germany in Bremen in February and Blanc said he would use the opportunities to have a look at players on the fringes of his first team.
"We'll be playing games in which there is nothing at stake but they'll be against top sides," he said.
"We'll put the emphasis on our play, but we'll also try to give time to players who haven't had many opportunities to play -- as long as they keep playing well for their clubs."
Qualifying France for next summer's tournament in Poland and Ukraine represents mission accomplished for Blanc, who had inherited a squad traumatised by the fall-out from last year's disastrous World Cup in South Africa.
Nasri's goal allowed France to extend their unbeaten run to 15 matches -- including friendly wins against England and Brazil -- but Blanc said qualification would not completely erase the pain of the Knysna mutiny.
"No. There will always be people who think about it and the press who talk about it," he said.
"And the players who were there will think about it too. You have to try to move on, but the scar will always be there."
Blanc's opposite number, Safet Susic, refused to comment on the penalty, which saw Sevilla defender Emir Spahic penalised for a trip on Nasri after the Manchester City midfielder had robbed him of the ball inside the penalty area.
"I've not seen it," he said. "I didn't understand what happened, so I can't give my opinion."
He was, however, full of praise for a team that had been just 12 minutes away from qualifying for the country's first major international tournament since Bosnia was granted independence from the former Yugoslavia in 1992.
"France are an exceptional team but we had control of the pitch for the first 60 minutes," said the former Paris Saint-Germain favourite.
"In the last 30 minutes, France got on top."
He added: "I congratulate France for their qualification. I hope we'll get more luck in the play-offs. I think my team deserves a place at Euro 2012."