The Metropolitan Police were notified after the attempted hack was discovered on New Year's Eve and blocked by BT, which hosts the secure payment area of the website.
The 28 year-old-man was arrested in London's Bishopsgate area last week. The man has since been bailed but is due in court in February over offences relating to the Computer Misuse Act.
Officers are now investigating computer equipment seized during the investigation.
The Met Police have stressed that site is still secure and has security systems designed to detect and block such attempts.
While the attempted hack was unsuccessful, some criminals have tried other means to make money out of the disaster. Some Chinese fraudsters have been manipulating Google rankings to try ensure their fake donations site ranks higher than the genuine one.
Another man was arrested and charged with sending fake charity emails asking for donations for a real relief organisation.