Bottles were thrown at police in Ladbroke Grove and at Oval
Police officers have criticised the decision not to equip them with riot shields and helmets at this year's Notting Hill Carnival in August.
Police were pelted with bottles in two stand-offs at the west London event, when 39 officers were injured.
An officer wrote on the Police Federation website: "We as an organisation failed to protect ourselves from members of the public."
The Metropolitan Police said it was examining feedback from the operation.
'Intent to injure'
Police were attacked by about 180 youths at south London's Oval cricket ground as they stopped the group from going to the carnival on 25 August.
Later officers were hit with bottles when they clashed with 40 people in a separate stand-off in Ladbroke Grove.
Officers complained about the lack of equipment in a Police Federation web forum.
One wrote: "Our kit was on a coach somewhere and at no point did we have access to shields on the coach."
The officer added: "There was specific intent to seriously injure police officers and yet again we as an organisation failed to protect ourselves from members of the public."
Deputy Assistant Commissioner Chris Allison, who had been responsible for policing the carnival, said the timing of when to deploy officers in riot gear was "not an exact science".
"To deploy officers too early in full kit can ignite and inflame the situation causing disorder to grow in size, scale and length with the potential of far more people being injured, these being both police officers and the public," he said.
However he denied placing "public perception" over the safety of officers.
Mr Allison said he had spoken to officers involved about their concerns and that a "full post-event investigation" was taking place.
A Met Police spokesman said the "vast majority" of injuries sustained by police during the carnival were minor.
A total of 330 people were held during this year's carnival with weapons such as knives, a Taser gun and CS spray being seized.