During PC Simon Harwood's cross-examination by Mark Dennis QC, he was asked:
"You do now accept that what you did in relation to Mr Tomlinson was wrong?"
Harwood replied: "Like I said, now I do, but not at the time."
He went on: "Now I've seen all the evidence and I know how poorly Mr Tomlinson was I'm sorry that I got involved, I shouldn't have hit him with a baton and pushed him."
Harwood, 45, from Carshalton in Surrey, denies manslaughter on the grounds that he used reasonable force.
The police officer accused of the manslaughter of Ian Tomlinson has said he now accepts that he was "wrong" to have hit and pushed him.
Jurors trying a policeman accused of killing Ian Tomlinson during the G20 protests heard Pc Simon Harwood had a "rush of blood to the head".