Qatar on Monday demanded neighbouring states lift their "blockade" of the emirate as a pre-condition for crisis talks, even as the United Arab Emirates warned its isolation could last years.
Foreign Minister Sheikh Mohammed bin Abdulrahman Al-Thani called measures imposed against Qatar by Saudi Arabia, the UAE, Bahrain and others "an act of aggression".
"We have to make it very clear for everyone, negotiations must be done in a civilised way and should have a solid basis and not under pressure or under blockade," he told reporters in Doha.
"Qatar under blockade -- there is no negotiation. They have to lift the blockade," said Sheikh Mohammed.
"Until now we didn't see any progress about lifting the blockade, which is the pre-condition for anything to move forward."
On June 5, Saudi Arabia and its allies cut all diplomatic ties with Qatar, pulling their ambassadors from the gas-rich emirate and giving its citizens a two-week deadline to leave their territory.
The measures also included closing Qatar's only land border, banning its planes from using their airspace and barring Qatari nationals from transiting through their airports.
Saudi Arabia, the UAE, Egypt, Bahrain and others accuse Qatar of supporting and funding "terrorism" and of working with regional rival Iran, charges Doha firmly denies.
Asked if the ultimate aim of the Gulf countries was to enforce regime change, the foreign minister replied: "No one is in a position of imposing regime change in this country.
"Our system here is based on a consensus between the people and its ruler."
- 'Isolation could take years' -
Sheikh Mohammed's demand came as a UAE state minister warned Qatar's diplomatic isolation could "last years".
"We do not want to escalate, we want to isolate," state minister for foreign affairs Anwar Gargash told journalists in Paris. "This isolation can take years."
Gargash said that while Qatar's rivals were "betting on time", a solution could not be brokered until it abandoned its support for "extremist Islamists".
"They have built a sophisticated podium for jihadism and Islamic extremism," he said.
"They support groups linked to Al-Qaeda in Syria, Libya... and in Yemen.
"This state is weaponising jihadists and Islamists, it is using this as a weapon of influence," he added.
Sheikh Mohammed said Qatar had not received any demands from the Gulf states or from countries seeking a diplomatic solution, including Kuwait, the United States, France and Britain, as the conflict dragged into its third week.
"Why they didn't submit their demands yet? For us, there is no clear answer for this," he said.
"But what we have seen until now, there is no solid ground for these demands, that's why they didn't submit their demands yet."
The foreign minister said the economic impact on Qatar had so far proved to be minimal, but added: "We are not claiming we are living in a perfect condition."
On Monday, Yousuf Mohamed al-Jaida, chief executive of the Qatar Financial Centre, said the "blockade" had put at risk business deals worth $2 billion in Arab countries that have cut ties with Doha.
- 'Worrying crisis' -
The Gulf political crisis has also affected countries outside the region.
"France, UK or the United States -- they are strong allies of Qatar and we have a great deal of cooperation together in terms of military, defence, security, economically," said Sheikh Mohammed.
"So a blockade on Qatar and measures being taken against Qatar in this way is affecting the interests of those countries as well, directly."
Concern over the ongoing crisis also surfaced at a meeting of European Union foreign ministers in Luxembourg on Monday, who said "the depth of the crisis is more worrying than at any time before".
EU foreign affairs chief Federica Mogherini called for "de-escalation" and encouraged "all Gulf countries to engage in political dialogue without pre-conditions".
Experts fear the crisis could draw in other countries. Adding to the growing tensions, Qatar announced Monday it had begun joint military exercises with the Turkish army.
Amnesty International has flagged the humanitarian cost of the crisis, warning it was "spreading fear" across the region.
Saudi Arabia, the UAE and Bahrain had given their citizens a June 19 deadline to leave Qatar, a deadline which came into force on Monday.