The opposition activist tweeted a photo of herself at Caracas' worldwide airport holding a document ordering the seizure of her passport.
Tintori, whose husband, opposition leader Leopoldo Lopez, is under house arrest, frequently travels overseas to campaign against President Nicolas Maduro's socialist government and denounce rights abuses.
French President Emmanuel Macron expressed concern this week over what he called the "dictatorship" in Venezuela, lamenting that Mr Maduro is "trying to survive at the cost of an unprecedented humanitarian distress".
That is equivalent to almost $11,000 at the widely used black market currency rate, and Tintori said they were personal funds intended mainly to cover medical costs for her hospitalized, 100-year-old grandmother. They can lock up people but not ideals. "The Venezuelan opposition must remain free".
In response to the declaration, Venezuelan Foreign Minister Jorge Arreaza fired back, demanding "respect" for Venezuela's "democracy and institutions".
"The UK hopes that Ms Tintori will be permitted to travel soon". None of the foreign leaders she was due to meet have yet reponded with comments on her situation.
Venezuela's opposition says the Maduro government has stepped up repression of opponents this year, while officials say they are acting to stop violent coup plots fomented by the United States and other foreign powers.
"The ambassadors were used by Mrs. Tintori, who had prepared a press conference, accompanied by ambassadors, knowing that she would not be able to leave Venezuela because of the case in which she is accused", said Arreaza. Leopoldo Lopez was sentenced to 13 years and nine months jail time for his role in leading 2014's violent anti-government protests that left 43 dead, the majority state security personnel, government supporters, and passerby. He served three years and five months in the Ramo Verde prison and remains under house arrest.
"The 200 million that Lilian had in the truck was not for her grandmother, [but] for the Popular Will activists", he claimed.