Francis, who vigorously opposed gay marriage in his native Argentina, and Archbishop Justin Welby chatted, prayed and had lunch together at the Vatican in their first encounter since both were installed in March.
Welby, the spiritual leader of the 77 million-strong Anglican Communion, has opposed legislation in Britain that would legalize gay marriage, saying it would undermine family life.
He appeared last week before the House of Lords before it moved the gay marriage bill a step closer to becoming law. The legislation would enable gay couples to get married in both civil and religious ceremonies in England and Wales.
In his remarks to Welby, Francis said he hoped they could collaborate in promoting the sacredness of life "and the stability of families founded on marriage." He noted that Welby had recently spoken out on the issue, a reference to his House of Lords testimony.
Significantly, though, Francis didn't say that marriage should be based on a union between a man and woman, which is how Benedict XVI and John Paul II routinely defined marriage.
Vatican officials said it was a diplomatic attempt to make his point without making a provocative pronouncement. Francis has steered clear of the gay marriage debate as it has recently roiled France and Britain, and in general has refrained from making headline-grabbing comments on hot-button current events.
As archbishop of Buenos Aires, however, the former Cardinal Jorge Mario Bergoglio didn't shy away from voicing strong opposition to gay marriage, though he was pragmatic in sensing Argentina was heading in that direction.
Realizing the church couldn't win the fight outright, Bergoglio urged his fellow Argentine bishops to lobby for gay civil unions instead, according to the then-cardinal's authorized biographer. The bishops shot down the proposal and the church lost the issue altogether when the South American nation legalized gay marriage in 2010 - the first country in the region to do so.
Bergoglio once called gay marriage an "anthropological step backward."
"If there's a private union, then third parties and society aren't affected," he wrote. "But if they're granted marriage rights and can adopt, there could be children affected. Every person needs a masculine father and a feminine mother to help them settle their identity."