The pontiff said families should be asking themselves whether they should cut down on their technology usage and spend more time with each other instead.
More than 80,000 people gathered for a World Meeting of Families festival at Dublin's Croke Park on Saturday night.
Pope Francis was treated to a special performance of Riverdance by a troupe of Irish dancers and of Ave Maria by Andrea Bocelli and Celine Byrne.
The pontiff said social media could serve to build a network of friendships and solidarity, but he warned it should only be used in moderation.
He said it was important that social media "never become a threat to the real life relationships by imprisoning us in a virtual reality and isolating us from the very real relationships that challenge us to grow".
Families, the Pope said, should question whether they should be cutting down on the time they spend on technology and be spending more quality time with each other.
"When you use social media too much you go into a sort of an orbit, when at the dinner table, instead of talking to each other within the family each of you uses his phone to connect with the outside world," he said. "Then you go into an orbit."
He said it was dangerous behaviour because it takes away "the completeness of the family" and leads individuals "to a fuzzy life without any substance".
Pope Francis told attendees that holiness was about the "saints next door", those ordinary people who reflect God's presence in the life and history of the world.
He said the vocation to love and to holiness was not something reserved for a privileged few.
The Pope highlighted the difficulties some families, who have to flee their homes in search of security and peace, have to endure.
"A family's love and faith can be a source of strength and peace even amid the violence and destruction caused by war and prosecution," he said.
The three words that every family needs to know, the pontiff said were "sorry, please and thank you".
Pope Francis made the crowd repeat after him "sorry, please and thank you" and he advised families not to go to bed angry.
"When you quarrel....say you're sorry," he said.
"Before the day is over that's when you have to make peace, and you know why, do you know why it's necessary to make peace before day is over? Because if you don't...it's very dangerous."
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