George Galloway was denied entry into America last week. The former Respect MP and notorious pro-Palestinian activist was due to speak in five US cities, but was barred from flying in from London by US authorities.
The Muslim Legal Fund of America, which organised the tour, said the ban was because of "visa problems".
Mr Galloway reportedly said that the decision to ban him was not political, but down to a "technical glitch at Heathrow Airport".
He added: "My office is now in touch with the embassy in London to fix it."
A blogger present at a venue where the controversial politician addressed a crowd via a video link, reported that Mr Galloway said: "Nothing will stop me. Not the government of what they call Israel; not the government of Canada or the US."
The tour was intended to follow a similar one in Canada earlier this month, which provoked anger from Jewish organisations. Despite the bar, Mr Galloway said he would still try and attend an event in Michigan in
January.
Last month he was disciplined by broadcasting standards monitor Ofcom for breaching the rules on impartiality during his Press TV show.