The Arabic-language Al Bayan newspaper and the television channel Dubai One reported the arrests, while Dubai police did not answer repeated calls for comment.
The arrests come as the United Arab Emirates, which hosts some 4,000 US troops fighting the Islamic State group, remains a crucial regional ally.
Al Bayan quoted Maj Saud al-Khalidi of Dubai police as saying an "African gang" broke into the emails of the five senior officials and "got highly confidential information." He said the US asked Dubai police for assistance.
Those arrested are between 24 and 26 years of age and had a list of "5 million bank accounts," as well as hacking software and millions of dollars in assets, he said.
The major said the three people had entered the UAE on visitor visas a few years ago.
The reports did not identify the White House officials targeted. Al-Khalidi reportedly said those suspects would be handed over to the United States for possible criminal trials. The US Embassy in Abu Dhabi did not respond to requests for comment.