U.S. President Donald Trump held a phone call with Israeli Prime Minister Benjamin Netanyahu on Monday following the first direct exchange of fire between Israel and Iran since a cease-fire took effect in April, according to a White House official.

The call came amid reports of an increasingly testy relationship between the U.S. leader and Netanyahu, with Trump calling his ally "crazy" during another recent phone call between the two.

Iran fired missiles at Israel overnight and Israel responded by targeting military sites in Iran, sparking fears of a new full-scale conflict.

"Israel and Iran must immediately stop 'shooting'," Trump wrote earlier Monday on social media.

A White House official confirmed Trump and Netanyahu spoke on Monday without giving further details.