Pope Francis says society should not create "walls but bridges" to encourage good relations among people, adding it was wrong to be spiteful and say "I'll make you pay for that".
US President Donald Trump has promised to build a wall on the border with Mexico and have the Mexicans pay for it. The Argentine-born pontiff did not mention Trump or that specific wall in his comments on Wednesday.
Speaking at his weekly general audience, Francis spoke of a Christian calling "to not raise walls but bridges, to not respond to evil with evil, to overcome evil with good".
He then improvised and added: "A Christian can never say 'I'll make you pay for that'. Never! That is not a Christian gesture. An offence is overcome with forgiveness, by living in peace with everyone."
Last year, in response to an answer about then-candidate Trump's views on immigration and his intention to build a wall on the border with Mexico, Francis said a man with those views is "not Christian".
He said in an interview last month that he would not form an opinion of Trump until he first had a chance to see specific policies the new US president would implement.
As Trump was taking office on January 20, Francis sent a message urging him to be guided by ethical values, saying he must take care of the poor and the outcast during his time in office.