In a preliminary report published late on Wednesday, the investigators did not say who they held responsible for the hack but said that both Britain and the United States were helping with their inquiry.
The Trump administration has given mixed signals on whether to isolate Qatar or bring it into talks with other Gulf nations.
President Recep Tayyip Erdogan called for the lifting of a blockade on Qatar on Friday after approving legislation on deploying Turkish troops there, as the Gulf state faces isolation imposed by fellow Arab states over its alleged support for terrorism.
The UAE welcomed president Trump's "leadership in challenging Qatar's troubling support for extremism", said Yousef Al Otaiba, ambassador to the US.
Qatari Foreign Minister Mohammed bin Abdulrahman al-Thani gives a press conference in Doha, on June 8, 2017.
On Tuesday, the UAE, Saudi Arabia, and Bahrain also ordered all Qatar Airways offices located in their territory to close.
Tillerson demanded that Qatar, as well as the other countries, take steps to curtail support for terrorism.
Here's what we know about the alleged NSA leaker's military record
Department of Justice for sending classified material to a news organization, poses in a picture posted to her Instagram account. She did use her Facebook page to speak freely about politics, including some scathing opinions on President Donald Trump.
Qatar's foreign minister said the country will never surrender to the pressure being applied by its Arab neighbours and will not change its independent foreign policy to resolve disputes that have put the region on edge.
Secretary of State Rex Tillerson told reporters at the State Department that in addition to "creating a hardship on the people of Qatar" the ongoing blockade by Saudi Arabia, the United Arab Emirates, Bahrain and Egypt is "hindering" the USA -led effort to combat Daesh. We call on Qatar to be responsive to the concerns of its neighbors.
Qatar says it intends to take legal action against those responsible.
"We ask Qatar and other nations in the region to do more and do it faster".
Saudi Arabia, Egypt, the United Arab Emirates and Bahrain severed their ties with Qatar on Monday, accusing it of supporting terrorism and Iran, opening the worst rift in years among some of the most powerful states in the Arab world. "Our position on countering terrorism is stronger than numerous signatories of the joint statement - a fact that has been conveniently ignored by the authors".
Several well-known figures whom the UAE has already labelled as terrorists are on the list, including Yusuf Qaradawi, the Egyptian-born preacher and spiritual leader of the Muslim Brotherhood, leaders of extremist militias in Libya, numerous Shia militants from Bahrain nd Yemeni Abdelwahab Al Humayqani, the secretary general of the Salafi Al Rashad Party and an adviser to Yemen's president.
He also said it was hurting American business in the area.