The Old Testament moral law is God’s eternal Law and is not abrogated by the Covenant of Christ.
Matthew 5:17 “Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.”
The Old and New Testament do not contradict each other in regard to imprecatory prayer and loving one’s enemies.
God called His people to love their enemies even in the Old Testament:
Proverbs 25
“21 If thine enemy be hungry, give him bread to eat; and if he be thirsty, give him water to drink:
22 For thou shalt heap coals of fire upon his head, and the Lord shall reward thee.”
The Psalms and Proverbs do not contradict each other.
In Matthew, Jesus is dealing with personal wrongs.
Those teachings to not contradict prayers that God gives to be prayed against His enemies.
One of the great heresies in America which took hold in the 19th century was the idea that Christians were supposed to stop restraining the most wicked sins against God and man based on the deceptive interpretation of Matthew 5. Such a heresy, after all, even would mean that a Christian must give up their right and responsibility of self-defense against criminals and attacks, which, of course, is nonsense.
Do you have a New Testament passage, or better yet, a quote from Jesus Himself, that we are to pray destruction on our enemies?