The Red Devils drew 1-1 with Anderlecht in the Europa League quarter-final first leg at the Constant Vanden Stock Stadium.
When Henrikh Mkhitaryan scored in the 36th minute, Ibrahimovic rallied his colleagues in a huddle and told them: "We need to do more."
But just as they have done so many times this season, United failed to make the most of their chances and were made to pay when Leander Dendoncker scored an equaliser on 86 minutes.
Zlatan will be hoping United can 'do more' when they host the Belgian side at Old Trafford in the return bout next Thursday.
Before that, however, is a glamour Premier League clash with champions-elect Chelsea at home on Sunday.