"Qatar has been a very great ally. Israel and everyone else, we have to be careful. When we attack people we have to be careful," Trump told reporters.

Trump initially rebuked Israel over Tuesday's unprecedented strike on Doha, where negotiators from Israel and Hamas have been working to end the war in Gaza.

The attack has prompted Arab and Muslim leaders -- including Palestinian president Mahmud Abbas -- to gather for a show of solidarity in Doha, where Qatar's Prime Minister Sheikh Mohammed bin Abdulrahman Al Thani urged the world to "stop using double standards" and hold Israel to account.

Israel's strike on the gulf country's capital killed five Hamas members and a Qatari security officer.

Qatar hosts the largest US military base in the region.