Projectiles including bottles and fireworks were launched at the visiting team's vehicle as they made their way to the stadium ahead of the quarter-final first leg.
Liverpool issued a public apology for the damage caused, condemning the actions of a few supporters "in the strongest possible terms" while offering their opponents support.
The club will also cooperate with authorities to help identify the individuals who were involved in the incident prior to their side's 3-0 win.
"We are aware that damage was caused to the Manchester City team bus as it approached Anfield stadium this evening ahead of the Liverpool v Manchester City match," Merseyside Police match commander superintendent Paul White said in a statement.
"Thankfully no-one on the bus was injured, but injuries were caused to two of our officers when projectiles were thrown towards the bus. The officers and stewards are there to protect the public and keep them safe.
"This behaviour by a number of people who threw bottles, cans and pyrotechnics towards the bus is completely unacceptable and we will conduct enquiries to identify who was responsible and bring them to justice.
"We worked very closely with both clubs to ensure the safety of the public and the teams themselves, and it is disappointing to see that a number of people behaved in this appalling way."
After the game, City manager Pep Guardiola was critical of the authorities for not doing more to avoid the episode occurring prior to a huge European fixture.
"I don’t know, maybe the people saw it on TV, I don't know. Yesterday you explained about that, it is going to happen, and it happened. I didn't expect that. I am new here," he told the media.
"Normally when the police know that is going to happen, they try to avoid it happening. I did not expect that from the Liverpool side, from the people."