The 24-year-old Norwegian was injured in Sunday’s 2-1 FA Cup quarter-final win at Bournemouth.
Having just scored his 30th goal of the season to level the tie, he was then hurt in a challenge with Bournemouth midfielder Lewis Cook.
The Premier League champions did not provide a timescale for the player’s return.
“The expectation is that Erling will be fit in time to play a further part in the remainder of this season, including this summer’s Fifa Club World Cup,” said a club statement.
“Erling underwent initial tests in Manchester on Monday morning and will now seek specialist consultation to confirm the full extent of the injury. Assessment remains ongoing to ascertain a full prognosis,” it added.
City are currently fifth in the Premier League and battling to ensure a spot in the Champions League next season.
Pep Guardiola’s side face matches against Leicester and Manchester United this week.
They then have a visit from Crystal Palace and a trip to Everton before their FA Cup semi-final against Nottingham Forest, at Wembley on April 26. (AFP)
