Sheikh Saif bin Ahmed Al Thani, Qatar's communications director, said the decision by the four Arab states to add 18 groups and individuals allegedly linked to Qatar to their "terrorist" list had no basis in fact.
"It comes as a disappointing surprise that the blockading countries are still pursuing this story as part of their smear campaign against Qatar," he said in a statement to Reuters news agency on Wednesday.
The move by Saudi Arabia, the UAE, Egypt and Bahrain on Tuesday came despite mounting international pressure to compromise in their weeks-old boycott of their fellow US ally.
The new names include nine entities in Yemen and Libya, and add to a previous blacklist of 59 individuals and 12 groups issued by the four states last month.
Sheikh Saif said: "This latest list provides further evidence that the blockading countries are not committed to the fight against terrorism.
"All individuals with links to terrorism in Qatar have been prosecuted. We encourage the blockading countries to spend less time on drafting these fabricated lists and more time on implementing measures to counter the threat of extremism in their own countries."
He said Qatar constantly reviews its anti-terror laws to "remain on the front foot in the fight against extremism and terror financing".
For his part, Anwar Gargash, UAE minister of state for foreign affairs, said via Twitter on Wednesday that it is important to look beyond "crisis" and to think of it as a "new set of relations in [the] Gulf replacing old ones".
He said the current state was set to continue and that "we have to go on without Qatar".
Saudi Arabia and its allies have been boycotting Qatar since June 5 in the region's worst diplomatic crisis in years.
Accusing Qatar of financing terrorism, they sealed the emirate's only land border, ordered its citizens to leave and closed their airspace and waters to Qatari flights and shipping.
They want Qatar to cut back ties with Iran, close down a Turkish military base in Qatar and shut the Al Jazeera TV channel, which they view as critical of their governments.
Qatar has dismissed the demands as a violation of its sovereignty and has received significant support from its ally Turkey.
Rex Tillerson, the US secretary of state, last week spent four days in the region trying to broker a settlement of the crisis. He has voiced satisfaction with Qatar's efforts to address any suspicion of terror funding.
On the other hand, after talks with Federica Mogherini, the EU diplomatic chief, on Tuesday, Sameh Shoukry, Egypt's foreign Mmnister, gave warning that the four governments would accept no compromise in their dispute with Qatar.
"We cannot compromise with any form of terrorism, we cannot compromise or enter into any form of negotiations," he said.
In Tuesday's statement, the four countries accused Qatari, Kuwaiti and Yemeni nationals of helping to raise funds for al-Qaeda fighters.
Their blacklist now include three Yemeni charities, three Libyan media outlets, two armed groups and a religious foundation, some of which are already subject to US sanctions.
Source: News agencies