Pope Leo XIV has said that he plans to continue speaking out against war after US President Donald Trump's direct criticism of him.
In comments aboard the papal flight to Algiers, where the first US pope is starting a 10-day tour to four African countries, the pontiff also said the Christian message was being "abused".
"I don't want to get into a debate with him," Pope Leo said. "I don't think that the message of the Gospel is meant to be abused in the way that some people are doing."
"I will continue to speak out loudly against war, looking to promote peace, promoting dialogue and multilateral relationships among the states to look for just solutions to problems," he said.
"Too many people are suffering in the world today," said Leo. "Too many innocent people are being killed. And I think someone has to stand up and say there's a better way."
Mr Trump, in an apparent response to the pope's growing criticisms of the US-Israeli war on Iran and the Trump administration's hard-line immigration policies, said Pope Leo was "terrible".
"Pope Leo is weak on crime, and terrible for foreign policy," Mr Trump wrote in a post on Truth Social.
Catholics on social media quickly lambasted Mr Trump for attacking the leader of the Church.
"There is no ambiguity about the situation now," Massimo Faggioli, an expert on the papacy, said.
He compared the comments to efforts by the leaders of Germany and Italy during World War II to draw the late Pope Pius XII to support their causes.
"Not even Hitler or Mussolini attacked the pope so directly and publicly," said Mr Faggioli.
Archbishop Paul S Coakley, president of the US Conference of Catholic Bishops, said he was disheartened by Mr Trump's comments.
"Pope Leo is not his rival; nor is the Pope a politician. He is the Vicar of Christ who speaks from the truth of the Gospel and for the care of souls," he said in a statement.
Leo, originally from Chicago, is the first US pope. Known for choosing his words carefully, he has emerged as an outspoken critic of the Iran war in recent weeks and decried the "madness of war" in a peace appeal on Saturday.
Last year, he questioned whether the Trump administration's hard-line immigration policies were in line with the Church's pro-life teachings.
"Someone who says, 'I am against abortion but I am in agreement with the inhuman treatment of immigrants in the United States', I don't know if that's pro-life," the pontiff said in September.
Mr Trump wrote in his post yesterday that "Leo should get his act together as Pope", later telling reporters he was "not a big fan" of the pontiff.
Mr Trump's broadside against Leo also accused him of being "weak on nuclear weapons," several days after the pope said the US president's threat to destroy Iranian civilisation was "truly unacceptable".
In a speech on Palm Sunday last month in St Peter's Square in the Vatican, the pope said God rejects the prayers of leaders who start wars and have their "hands full of blood," calling the conflict in Iran "atrocious".
Leo has also called on Mr Trump to find an "off-ramp" to end the conflict and "decrease the amount of violence".
In his post, Mr Trump suggested that Leo was only elected to lead the Catholic Church last year "because he was an American, and they thought that would be the best way to deal with President Donald J. Trump".
The Vatican did not immediately respond to a request for comment.
The pope's call for a more compassionate approach to immigration - a sentiment expressed by several of Leo's predecessors - stands in contrast to the stance of Mr Trump, who has argued that the US must curtail immigration from developing countries to reduce crime.
"He's a very liberal person and he's a man who doesn't believe in stopping crime," Mr Trump told reporters last night.
Mr Trump also had a rocky relationship with Leo's predecessor, Pope Francis, who criticised Mr Trump's immigration policy proposals when he first ran for president and suggested Mr Trump was "not a Christian".
Mr Trump had called Francis "disgraceful" in early 2016.
