The Sweden international has expressed his satisfaction with his side's 4-0 win on Wednesday night, but added that the Scudetto holders are not assured of a quarter final place
The former Barcelona attacker praised the Rossoneri's mentality in the first leg of the tie, but stressed that it's not over yet as anything can happen in the return fixture on March 6.
"It was a night of great emotion because we won a difficult match with a great result and the side played brilliantly. You don't beat Arsenal 4-0 every day," Ibrahimovic was quoted as saying on the Uefa website.
"We are happy to take this first leg result over to London. Everybody helped each other out, we played with a great tempo, we played intelligently and everyone showed a great will to win. Above all, we showed the right mentality tonight.
"However it's not over yet. This is only the first leg. We'll have to stay focused for the return in London and then we'll see how we get on," the Scandinavia forward stated.
Milan will now turn their attention to the upcoming Serie A match away to Cesena on Sunday.
Meanwhile, Ibrahimovic still awaits a decision on his appeal against the three-match ban he got for his dismissal in the league game against Napoli, and no verdict is expected until February 23.