Trump said the United Arab Emirates, Saudi Arabia, Qatar and others that were previously funding terrorism had stopped such activities.
The emir will also be joining the president for a working lunch that the White House said would focus on security and economic issues.
Trump hasn't recently repeated the charge about Qatari funding for extremism, and US officials have credited Qatar with making progress in cracking down and improving transparency.
The whirlwind PR tour of the USA by Saudi crown prince Mohammed bin Salman has put a bright spotlight on the Kingdom's spat with Qatar.
The Persian Gulf Arab country is a long-standing American military ally and host to the largest U.S. air base in the Middle East. Al-Udeid air base also houses military personnel from the United Kingdom and other allies.
The announcement was made ahead of a meeting between Qatari Emir Tamim bin Hamad Al Thani and US President Donald Trump on Tuesday.
Trump and Abu Dhabi Crown Prince Sheikh Mohammed bin Zayed of the United Arab Emirates agreed on Friday to push for unity among Gulf nations, the White House said, amid a bitter standoff between Qatar and other USA allies in the region. "We are cooperating with the United States of America to stop funding of terrorism around the region". In a phone call last week, Mr. Trump credited the emir with working to counter terror financing and extremism. Qatar denies the allegations and says the moves attempt to undermine its sovereignty.More news: English Premier League Report, Chelsea v West Ham, 08 April 2018
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The emir said, "We do not and we will not tolerate with people who fund terrorism".
Saudi Arabia and its regional allies, the UAE, Bahrain and Egypt, launched a diplomatic and trade boycott against Doha a year ago, and Trump initially appeared to take Riyadh's side.
Qatar has sought to stress its role as a reliable and agreeable USA partner in a strategically vital region.
"He's a friend of mine" Trump said effusively.
There have been other signs that Trump is warming to the Qataris.
Trump went on to note Qatar's purchases of U.S. weaponry, saying they buy "a lot of equipment from us, a lot of military airplanes, missiles".