Israel has said it will respond to cyber-attacks in the same way it responds to violent "terrorist" acts after the credit card details of thousands of its citizens were published online.
A hacker named OxOmar claiming to be Saudi said on Thursday he had leaked the private information.
Credit card companies say at least 6,000 valid cards have been exposed.
Reports say OxOmar may be a 19-year-old living in Mexico.
Such cyber-attacks are "a breach of sovereignty comparable to a terrorist operation, and must be treated as such", Deputy Foreign Minister Danny Ayalon has said.
"Israel has active capabilities for striking at those who are trying to harm it, and no agency or hacker will be immune from retaliatory action," he added, without giving further details.
An aide to Mr Ayalon said Israel was aware of the report OxOmar may be in Mexico, but had not yet requested help from the Mexican authorities, Reuters news agency reports.