"It was a hard-fought game and in the first half the team held out well, but we conceded that Ibarbo goal right before the break," said Allegri.
"In the second half we started playing again and after the penalty had chances to win it. Unfortunately we were out of time and weren't sharp enough.
"We come away from Sardinia with a deserved point against a good Cagliari side."
For the second game in a row, Balotelli converted a late penalty to give Milan points.
"I never watch spot-kicks We should've been more wide awake on the Ibarbo goal, as we conceded just 40 seconds from half-time."