Inter defender Marco Materazzi suggested Milan were "frightened" of the Treble-winners.
"Not in my view," replied Ibra. "The Scudetto is ours to lose. If we don't get it wrong, then we will win."
Ibrahimovic scored one goal and created another for Robinho, despite Mark Van Bommel's red card.
"It seemed as if the Catania players were looking for that second yellow card. They found it, but we won with character.
"It's a good sign for the season, as it shows we are doing everything possible to win. It was a tough game against an aggressive and gritty side.
"In my view it was actually easier to play with 10 men, as that created more space for the forwards."