Qatar said Thursday it will not "surrender" and rejected any interference in its foreign policy, defying its Gulf neighbours in an escalating dispute over its alleged support for extremists.
"If there is any sensible argument or sensible accusation, we are ready to answer", Sheikh Mohammed said.
Meeting on the sidelines of a regional security summit in Kazakhstan, Chinese Foreign Minister Wang Yi told Iranian Foreign Minister Mohammad Javad Zarif that peace and stability in the Gulf accords with the common interests of the region and the global community.
Sheikh Mohammed's hard line mirrored that of a top Emirati diplomat who told the AP on Wednesday that the United Arab Emirates believes "there's nothing to negotiate" with Qatar.
"The Chadian government calls on all concerned states to privilege dialogue to solve this crisis and asks Qatar to respect its commitments by ceasing any attitude likely to harm cohesion of states in the region and peace in the world", the foreign ministry statement said.
"There can not ever be a military solution to this problem".
Saudi Arabia, the United Arab Emirates, Bahrain, Egypt and Yemen have accused Qatar of supporting regional terror groups, allegations denied by the Qatari government. "Leaders pointed to Qatar - look!"
Bahrain, Saudi Arabia, the United Arab Emirates (UAE) and Egypt severed relations with Doha on Monday, accusing it of supporting Islamist militants and their arch-adversary Iran - charges Qatar calls baseless. In an interview published by Saudi-owned Asharq al-Awsat newspaper, Sheikh Khalid bin Ahmed al-Khalifa said conditions posed by the four countries for a resolution of the crisis were "crystal clear".
UAE ruling family member: Qatar now questioning its leaders
Analysts have raised the prospect of a palace coup in Qatar, a hereditary monarchy with a history of such changes in leadership. Kuwait's Sheikh Sabah Al Ahmad Al Sabah met Qatar's emir, Sheikh Tamim bin Hamad Al Thani , when he arrived last night.
Turkey's parliament on Wednesday approved deploying troops to a Turkish base in Qatar under a previously agreed plan, in a move seen as a sign of support for Doha.
Trump initially took sides with the Saudi-led group before apparently being nudged into a more even-handed approach when USA defence officials renewed praise of Doha, mindful of the major US military base hosted by Qatar that serves, in part, as a launchpad for strikes on Islamic State insurgents.
In addition, some banks in Saudi Arabia and the UAE are closing out Qatari riyal long positions and offloading part of their riyal assets to reduce their risk.
But a Qatari official said on Thursday the emir would not be accepting the invitation. Qatar can survive "forever" despite crisis, he added.
"This is a foreign policy that has gone wild", state minister for foreign affairs Anwar Gargash told AFP. "We need to put everything in check".
The Abu Dhabi Petroleum Ports Authority also reimposed a ban on oil tankers linked to Qatar calling at ports in the UAE, reversing an earlier decision to ease restrictions and potentially creating a logjam of crude cargoes.
The United States, France and Russian Federation have called for dialogue while Turkey has defended Qatar and said it would further "develop" ties with Doha.
Qatari investigators have said that a cyber attack which caused the publication of fake news last month that helped trigger a crisis with Gulf neighbours was prepared in April.