The Post said officials became aware of the UAE's role in the hack after newly analyzed information gathered by members of the USA intelligence community revealed senior members of UAE's government discussed the plans and how to implement the attack.
"What is true is Qatar's behaviour", he added. Funding, supporting, and enabling extremists from the Taliban to Hamas and Gadhafi. "Inciting violence, encouraging radicalisation, and undermining the stability of its neighbours", the statement said.
Saudi Arabia and its allies imposed sanctions on Doha on June 5, including closing its only land border, denying Qatar access to their airspace and ordering their citizens back from the emirate. The hack also involved the planting of damning false stories about Qatar's emir.
Qatar said in late May that hackers had posted fake remarks by the emir, an explanation rejected by Gulf states.
UAE Minister of State for Foreign Affairs Anwar Gargash told the BBC on Monday the Post's report was "untrue".
Qatari officials have maintained that the quotes were part of an elaborate information warfare operation and have said they had tied parts of it to iPhones located in nearby countries, but never singled out a specific actor or nation.
The Federal Bureau of Investigation was previously known to be working with Qatar to probe the hacking.
"These are certainly developments that will be analysed and will have a major role to play in negotiations coming up", she said.
"We've sent a message to Qatar".
"We need to be certain that Qatar, a state with $300 billion in reserves, is no longer an official or unofficial sponsor of jihadist and terrorist causes", he said, giving no further detail on the proposed monitoring.
Last month, Mr Al Otaiba's emails were hacked and released by a group linked to Qatar called GlobalLeaks.
"And now the results are out in public and they confirm that hacking has taken place and the quotes that precipitated this crisis by the emir of Qatar were fabricated and resulting from this hacking".
Qatar has been subjected to a diplomatic and economic blockade that the USA government says could compromised U.S. efforts against so-called Islamic State.