Southgate furiously accused Ronaldo of diving to win a penalty in last term's corresponding fixture, sparking a war of words with United manager Sir Alex Ferguson, who branded the Boro boss "naïve".
But Southgate said: "We have got no issue with Cristiano Ronaldo. We all admire him as a player, we think he is an outstanding player and we respect him for that.
"He is certainly the best player in our league and if there is a better player in Europe we haven't seen much of them. His scoring record is phenomenal and he is a great talent.
"There were a couple of incidents in games last season but that is in the past. We respect what he's about, we respect his ability and as fans of good football we enjoy watching him play."