God had declared the destruction of all mankind,  “It repented God that he had made humankind”.  Some say that this should be translated that God regretted making humans.  It really does not matter, it all comes out in the same place concerning the new resolve and actions of God.  God gave a rainbow.  The rainbow was a promise of future mercy and not destruction.  God not only hung a rainbow in the sky, He hung one over His throne (Revelation 4:3) as a testimony of His everlasting mercy.  God has a preference for mercy over condemnation.  He wants none to perish.  He does not will our destruction; He wants us to align ourselves with His mercy by repentance. 

“The Lord saw that the wickedness of man was great in the earth, and that every intention of the thoughts of his heart was only evil continually. And the Lord regretted that he had made man on the earth, and it grieved him to his heart. So the Lord said, ‘I will blot out man whom I have created from the face of the land, man and animals and creeping things and birds of the heavens, for I am sorry that I have made them.’  But Noah found favor in the eyes of the Lord.” Genesis 6:5–8 (ESV).