Police were called to Cotts Close, W7 at 17:26hrs on Wednesday 30 April to reports of an assault.
Upon arrival officers were confronted by a man in his forties who armed with a knife.
The man attempted to attack the officers with the knife.
One male officer received an injury to his leg. He has been taken by London Ambulance Service to a west London hospital. His injuries are not believed to be serious.
No other officers were injured in the attack.
One man, in his forties, has been arrested on suspicion of GBH and has been taken to an West London Police Station.
Enquiries are continuing.
Police in Ealing continue to investigate