Romans 12:19 - Dearly beloved, avenge not yourselves, but rather give place unto wrath: for it is written, Vengeance is mine; I will repay, saith the Lord.
2 Corinthians 7:11 - For behold this selfsame thing, that ye sorrowed after a godly sort, what carefulness it wrought in you, yea, what clearing of yourselves, yea, what indignation, yea, what fear, yea, what vehement desire, yea, what zeal, yea, what revenge! In all things ye have approved yourselves to be clear in this matter.
We are not to seek vengeance when it comes to other people around us, it is up to God to seek Vengeance against other humans, however there is one thing where we can seek vengeance, and that is against our flesh and our sins. Our greatest enemy than any other humans is our flesh.