Manchester City assistant coach Manel Estiarte posted footage of Liverpool fans damaging the team bus on its way to Anfield on Wednesday night.
The sound of objects, including bottles and cans, striking the vehicle can be heard in the video posted on Instagram. The footage was filmed from inside the bus as it drove slowly toward the stadium for a Champions League quarterfinal match.
Estiarte responded to his own post, writing: "No words. Unacceptable."
Estiarte's video, seen below, contains some obscene gestures from the crowd.
Merseyside Police are conducting enquiries to identify those responsible for throwing objects at the bus after two officers were injured. Liverpool have condemned the attack and vowed to support City in establishing the facts of what occurred.
The City bus was deemed unusable for the return journey because of the damage caused to it, and the club had to supply a replacement.
UEFA announced on Thursday it has opened disciplinary proceedings against Liverpool.
After Wednesday's events, the focus will shift to the Etihad Stadium next Tuesday and the plans that are in place to avoid any similar incidents.
Liverpool will not say whether they will take extra steps to ensure the safety of their coach and players, but it is reported they are likely to have talks on the matter before next week.
"The club doesn't comment on any additional or exceptional security and safety measures implemented as pertains to its employees," a Liverpool spokesman told Press Association. "This applies to matters involving first-team travel plans also."
Arrangements for team arrivals at the Etihad are slightly different to other grounds, although both arrive on "protected" routes.
The home coach typically pulls up outside the main reception for the players to receive an organised and staged blue-carpet reception from assembled supporters. The away bus arrives at a separate location some distance away from where home fans congregate and has a private entry into a tunnel under the stadium.
Press Association reported that, at this stage, there are no plans to put in place any additional measures.