The island nation's Buddhist leaders are opposed to introducing a new constitution, for fear it may reduce their influence among the population of 21 million.
US Secretary of State Rex Tillerson says the test, on the eve of the U.S. Independence Day holiday, represented "a new escalation of the threat" to the United States and its allies.
Trump issued the travel ban amid rising international concern about attacks carried out by Islamist militants like those in Paris, London, Brussels, Berlin and other cities.
Foreign ministers and defense officials of the three neighboring countries agreed to work together to track communications and crack down on the flow of arms, fighters and money.
The tightening of anti-terrorism laws in the world's largest Muslim-majority country comes as concern grows about the spread of influence of Islamic State.
The offensive came amid worry that rebel reinforcements could arrive in the city after Eid al-Fitr, which marks the end of the Muslim holy month of Ramadan.
The San Francisco-based 9th US Circuit Court of Appeals used narrow grounds to reject the Trump administration's bid to undo a Hawaii federal judge's decision blocking the temporary ban.
The Philippines military says the United States was providing technical assistance to end the siege of Marawi City by fighters allied to Islamic State.