Steven Gerrard was furious after Aston Villa goalkeeper Robin Olsen was attacked by a Manchester City supporter following the full-time whistle at the Etihad on Sunday.
Thousands of City fans spilled out onto the pitch after their 3-2 victory over Gerrard's side.
After full-time, Villa's debutant goalkeeper Olsen was seen holding his head before making his way down the tunnel.
Asked if Villa players made it off the pitch OK, Gerrard replied: "No is the answer to that. My goalkeeper was attacked and I think those questions should go to Pep and Manchester City. We'll go and check if he's OK now."
City later apologised to Olsen and vowed to indefinitely ban the fan who attacked the goalkeeper.
Supporters have run onto the field after a number of recent high-profile Premier League and EFL matches, with a Nottingham Forest fan jailed for 24 weeks after headbutting Sheffield United’s Billy Sharp.
Crystal Palace manager Patrick Vieira was involved in an altercation after Everton fans invaded the pitch on Thursday and fans streamed onto the field on Sunday after City’s 3-2 comeback win against Aston Villa which secured the Premier League title.
City swiftly released a statement apologising to Olsen.
“Manchester City would like to sincerely apologise to Aston Villa goalkeeper Robin Olsen, who was assaulted after the final whistle at today’s match when fans entered the pitch,” the club said.
“The club has launched an immediate investigation and once identified, the individual responsible will be issued with an indefinite stadium ban.”
City manager Pep Guardiola admitted the incident had been the low point of the day.
Guardiola said: “I’m so sorry on behalf of the club to Olsen and Aston Villa.
“I don’t think there were intentions, but the emotions of people there, it’s always difficult to understand why people respond in that way and cannot celebrate themselves and not do these kind of things. Hopefully we can discover who the person was and he’ll be punished.
“I don’t know how (to stop it). You cannot put 1,000 guards to control all the people there. We are so sorry. It’s the bad news of today.”
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