Sheikh Mohammed bin Abdulrahman Al-Thani called measures to isolate Qatar imposed by Saudi Arabia, the United Arab Emirates, Bahrain and others "an act of aggression", adding that lifting them was a "pre-condition" for talks.
"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," the foreign minister told reporters in Doha.
"Qatar under blockade -- there is no negotiation. They have to lift the blockade."
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.
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Saudi Arabia, the UAE, Egypt, Bahrain and other states accuse Qatar of supporting and funding "terrorism" and of working with regional rival Iran, charges Doha firmly denies.
Sheikh Mohammed's demand came as a UAE minister warned that 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 during a visit to Paris. "This isolation can take years."
Sheikh Mohammed said that 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.
"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 added that the economic impact on Qatar had so far proved minimal but added: "We are not claiming we are living in a perfect condition."
"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.