If Limited Atonement (Christ only died for the elect) is true, then God does not love His enemies.
When God tells us to love our enemies, He is asking us to do something more than He did. He’s calling us to a higher morality than His own.
If we did love our enemies, our love and morality would be of a nobler quality, thus making us better than God.
You either conclude that, or you conclude that Limited Atonement is in error and God is calling us to be like Him, who loved His enemies and laid down His life for them.