The Catholic and Protestant traditions revere the Lord Prayer, which says in part:
"And forgive us our debts, as we forgive our debtors."
Immediately after telling His disciples to pray that way, Jesus gives us more details about forgiveness:
"For if you forgive men their trespasses, your heavenly Father will also forgive you. But if you do not forgive men their trespasses, neither will your Father forgive your trespasses."
In other words, Christians are to forgive others if they wish God to forgive their own offenses. (Jesus was emphatic on this point when He explained about forgiveness with the Parable of the Unforgiving Servant in Matthew 18:21-35.)
I have not seen any literature where the Catholic and Protestant perspectives differ in this regard when they are talking about this passage of Scripture.