Britain fired the gun on a two-year countdown to leave the European Union Wednesday when an official letter was handed to EU Council President Donald Tusk.
"If the British government went to Trump today and said right, let's crack on, I think that certainly by the end of this year if not a considerable time before, a trade deal could be done," he said.
"But the problem is we are not allowed to, because Mr. (Jean-Claude) Juncker says we can't do it until we have left the European Union," said Farage outside Westminster.
Farage also spelled out the disbelief he witnessed in the U.S. at the restrictions Europe places on Britain.
"The White House is very positive about the Anglo-American relationship in terms of trade, in terms of security, in terms of defense," he said.
"They look on with incredulity that a British prime minister is told by a Brussels based bureaucrat that we are not allowed to sign a deal," he said.
Jean-Claude Junker is the president of the European Commission, the executive arm of the EU.