A policewoman told newspaper seller Ian Tomlinson after he was shoved to the ground: "It's obvious mate, you can't come through", an inquest into his death heard.
Pc Kerry Smith said Mr Tomlinson was not posing a threat to police and she could tell he was not a demonstrator, but he had been repeatedly told he could not come past the cordon.
She said she was shocked by the forcefulness of the push which sent the 47-year-old to the ground and had seen no reason why such an action might have been necessary.
On the second anniversary of Mr Tomlinson's death, she told the inquest at the International Dispute Resolution Centre in Fleet Street, London: "He sat up and looked towards us and he said 'I just wanted to go home'.
"I said 'It's obvious mate, you can't come through'."
Pc Smith, based in Fulham, with more than seven years' service in the Met, wrote in notes after the incident: "Officer left of me pushed him. He went forward. Thought he hit head. Expected blood.
"He sat up, looked around, said 'I just want to go home'. Dazed, shocked.
"I said 'Mate, it's obvious, you can't go that way'."
Pathologist Dr Freddy Patel found Mr Tomlinson died of natural causes after he collapsed during the G20 protests in London on April 1 2009.
But amateur video footage later showed shortly before his death he was pushed in the back by Pc Simon Harwood and landed heavily on the ground. He got up and staggered about 100 yards before falling to the ground for the final time. The hearing continues.