The investigation targeting the 87-year-old founder of the FN, who was expelled from the party earlier this year, was opened by financial prosecutors in June over suspicions he had stashed money abroad and failed to declare property, a judicial source said.
Le Pen said the search was an "unjustified act of judicial violence".
Anti-corruption investigators are looking into a holding in the British Virgin Islands which is linked to an account in Geneva operated by Le Pen's personal assistant, said a source close to the probe.
The Virgin Islands account was closed last year and the funds moved to a bank in the Bahamas, the source added.
French media company Mediapart reported the investigation into the Geneva trust earlier this year, saying it contained at least €2.2 million ($2.4 million), most of it in gold bullion and coins.
"I once again deny in any way breaking the law," he said Wednesday. "I have been subject to minute, even inquisitorial, attention by tax authorities for dozens of years."
"As always, whether it's under a left or right government, it seems the electoral calendar demands these legal and if possible media trials," he added.