The seven-time world champion was handed a 10-place grid penalty for the next race after the defensive move forced Barrichello to within centimetres of a concrete wall as the pair jostled for 10th place.
Schumacher, 41, initially denied making a mistake, but, on reflection, now accepts he was in the wrong.
“Right after the race I was still in the heat of the action,” Schumacher said. “But after watching the moment again with Rubens, I must say the stewards were right in their assessment: the manoeuvre against Rubens was too dangerous.”
“I wanted to make it hard for him to pass me but I didn’t want to endanger him with my manoeuvre,” added the Mercedes driver. “If he has this feeling I am sorry, this was not my intention.”
Meanwhile, Lewis Hamilton has warned McLaren that his team’s title hopes are hanging by “a thin thread” after the British driver failed to finish Sunday’s race due to a gear box failure.
Red Bull’s Mark Webber overtook Hamilton at the top of the driver’s championship with his fourth win of the season in Hungary as McLaren dropped to second place in the constructors’ standings.
“It’s going to be very hard, these seven races,” said Hamilton. “We’re holding on by a thin thread at the moment.”
“If they [Red Bull] continue with the pace they have, then we really don’t have a huge hope. But I do believe that we can catch them,” added the 25-year-old.
Webber’s win in Hungary saw the Australian open up a four-point lead over Hamilton at the top of the drivers’ championship with McLaren now trailing leaders Red Bull by eight points in the constructors’ standings.