Manchester United beat Saint-Etienne 3-0 in the first leg of their last-32 UEL encounter and Ibrahimovic scored all three.
Mourinho praised the veteran attacker for his contribution to the match, as he continues to impress in his first season in the Premier League.
And while Mourinho was pleased with Ibrahimovic , the clean sheet his men kept made him happier.
“He has scored so many hat-tricks in his career but this is a first for Manchester United,” the Portuguese tactician told MUTV.
“We know that it is more difficult in England, we know clearly that it is fantastic for him.
“But the important thing is the result and the important thing is that we managed a clean sheet at home, which is important, and to score three goals is a good advantage for us.
“We can try to manage with that.”
Ibrahimovic has scored an impressive 23 goals in 35 appearances in all competitions for United this season.