The author of Psalm 94 asks God to intervene when the bad guys appear to be getting away with murder. Vengeance is the Lord’s (v. 22-23).
The author cries out to God to avenge his people in Psalm 79, asking forgiveness for the sins of previous generations (v. 8).
We are called to show mercy, even though sometimes our human nature wants revenge. Talk to God about anything weighing on your heart.