"That (the) U.S. arms a terrorist group is what causes instability", Khameini wrote on Twitter Monday.
Those attacks, which left at least 12 people dead, were claimed by ISIS.
A senior Qatari counter-terror official has denounced a diplomatic and economic embargo imposed by Saudi Arabia and its regional allies saying Doha will not surrender to a "policy of domination and control". "Pakistan believes in unity among Muslim states and has made serious efforts for its promotion", said foreign office spokesperson Nafees Zakaria.
While Saudi Arabia has been threatened by the group, officials in the region and their Western counterparts have claimed ISIS receives funding from backers inside the Kingdom as well as from other rich Middle Eastern countries.More news: Rafael Nadal dominates in winning record 10th French Open
Qatar, which imported 80 per cent of its food from bigger Gulf Arab neighbours before the diplomatic shutdown, has also been talking to Iran and Turkey to secure food and water. Qatar has also accused Saudi Arabia of backing the militant group.
A senior counter-terrorism adviser to Qatar's foreign minister has hit out at the diplomatic squeeze on Doha by several Gulf states, calling it a "policy of domination and control". Our foreign assets and our foreign investment is more than 250% of our GDP.
The head of Iran's livestock exporters said they had exported 66 tonnes of meat to Qatar in the last two days.
"Qataris were affected because they were unable to see their relatives in Saudi Arabia, the UAE and Bahrain. By mid-July, it will cover one- third of Qatar's demand", Al Khayyat said. Leaders and representatives of 55 Arab and Muslim countries were in attendance.
Some of those countries, as well as nations in Asia and Europe, rely on supplies from Qatar, the world's largest exporter of liquid natural gas.More news: Israel approves over 8000 new West Bank Housing units
Saudi state news agency SPA reported late on Sunday that King Salman has ordered authorities to "take into consideration humanitarian situations of Saudi-Qatari joint families", appearing to clarify the previous announcements.
"We were not allowed to give refunds to our passengers", he said.
In all, 18 destinations in the region are now out of bounds for Qatar Airways, which has also been forced to close its offices in Saudi Arabia and the UAE.
Erdoğan that he would hold a joint phone call Tuesday with French President Emmanuel Macron and Qatari Emir Tamim bin Hamad Al Thani to discuss the recent developments.More news: Russian police may use force to break up illegal Moscow rally