The incident happened last night when George Galloway was posing for pictures with people on Golborne Road in Notting Hill when a man shouting about the Holocaust assaulted him, the MP's spokesman said.
Galloway was interviewed under caution by police earlier this month after he made controversial comments about Israel.
Galloway, an MP from Bradford West of Respect Party had said in a speech earlier this month that "Bradford had been "declared an Israel-free zone" and asked people to reject all Israeli goods, services academics and tourists.
The pro-Palestine Bradford West MP, spent the night in an hospital and is also being treated for a suspected broken rib and bruising.
Police arrived quickly on the scene and the man was arrested on suspicion of causing actual bodily harm.