Inter-racial marriage implies that there are races. In the Old Testament, God forbade the Israelites from marrying people from other countries/cities/cultures. This was not done out of racial difference or prejudice but because the other people were pagans. They sacrificed their children to their idols and did other terrible things that resulted in their eventual destruction. We can see from Old Testament history what happened when the Israelites intermingled with those from pagan societies—they adopted their vile practices and lived in sin, forgetting all that God had done for them.
Regarding marriage, God does not forbid the marriage between a light skinned and dark skinned person, but he does forbid the marriage between a Christian and non-Christian (2 Cor. 6:14), and the reason for that is because of the problems stemming from the Old Testament Israelites falling away from their faith. Marriage is a blessed union, but it can be very difficult and requires 100% effort from both husband and wife. How much harder marriage is when the couple doesn’t agree on spiritual matters!