Pope Francis (pictured) on Thursday urged the United States and Iran to avoid escalation and pursue "dialogue and self-restraint" to avert a wider conflict in the Middle East.

The pope made his appeal, his first direct comment on the current crisis, in a yearly speech that has come to be known as his "State of the World" address to ambassadors accredited to the Vatican.

Speaking for nearly 50 minutes in the Vatican's frescoed Sala Regia, the 83-year-old Roman Catholic leader offered a mostly grim overview of 2019, speaking of wars, global warming, xenophobia towards migrants and the danger of nuclear weapons.

"Particularly troubling are the signals coming from the entire region following the heightening of tensions between Iran and the United States," Francis told the diplomats from more than 180 states.

He said the tensions risked "compromising the gradual process of rebuilding in Iraq, as well as setting the groundwork for a vaster conflict that all of us would want to avert".

"I therefore renew my appeal that all the interested parties avoid an escalation of the conflict and keep alive the flame of dialogue and self-restraint, in full respect of international law," he said.

US President Donald Trump has suggested Iran was "standing down" after it fired missiles at US forces in Iraq on Wednesday, itself an act of retaliation for the Jan. 3 U.S. strike that killed Iranian commander Qassem Soleimani.

"Our human family is scarred and wounded by a succession of increasingly destructive wars that especially affect the poor and those most vulnerable," Francis said.

"Sadly, the New Year does not seem to be marked by encouraging signs, as much as by heightened tensions and acts of violence," he said.

Recent tensions could likely make it impossible for Francis to visit Iraq, which he has said he would like to do this year.

Wars and conflicts have led to an exodus of Christians from Iraq and some other countries in the Middle East.

Iraq's small Christian population of several hundred thousand suffered particular hardships when Islamic State controlled large parts of the country, but have recovered freedoms since the jihadists were pushed out.

Iraq is home to many different eastern rite churches, both Catholic and Orthodox.

Francis said he still hoped to make a visit this year to mostly Christian South Sudan, which is emerging from civil war.

The pope wove his speech around the foreign trips he made in 2019, which included a visit to Abu Dhabi in the United Arab Emirates. There, he became the first pontiff to set foot on the Arabian peninsula, home to Islam's holiest sites.

Speaking of climate change, he said it was sad that the urgency to tackle it "seems not to have been grasped by international politics".

He said last December's U.N. conference in Spain raised "serious concern about the will of the international community to confront" the issue.