A senior United Arab Emirates official has urged a quick end to the Iran-Israel war, warning of a "difficult aftermath" if the conflict is prolonged.

Anwar Gargash, diplomatic advisor to the oil-rich UAE's President Sheikh Mohamed bin Zayed Al Nahyan, said the war was "setting back" the wealthy Gulf region.

"The longer a war takes, the more dangerous it becomes," he told journalists in a briefing on Friday.

"I think any extended confrontation or war between Israel and Iran will only bring a very difficult aftermath."

US President Donald Trump has given Iran a "maximum" of two weeks to negotiate before possible US air strikes but Tehran said it would not hold talks while under attack.

"De-escalation is extremely important," Gargash said. "We still feel that there is a path back to negotiations on these issues."

The Middle East is still dealing with the repercussions of the 2003 US-led invasion of Iraq, which toppled Saddam Hussein but left the country divided and destabilised.

One major risk of the current war is disruption to the Strait of Hormuz between Iran and the Arabian Peninsula, which carries one-fifth of global oil output.

"This war flies in the face of the regional order the Gulf countries want to build, which is focused on regional prosperity," Gargash said.

"We feel that this is setting us back, not only us in the UAE, but I would say the region."