Acts 16
6 Now when they had gone through Phrygia and the region of Galatia, they were forbidden by the Holy Spirit to preach the word in [a]Asia. 7 After they had come to Mysia, they tried to go into Bithynia, but the [b]Spirit did not permit them. 8 So passing by Mysia, they came down to Troas. 9 And a vision appeared to Paul in the night. A man of Macedonia stood and pleaded with him, saying, “Come over to Macedonia and help us.” 10 Now after he had seen the vision, immediately we sought to go to Macedonia, concluding that the Lord had called us to preach the gospel to them.

I did a little research and found this:
“Asia” in the Book of Acts is modern day Turkey or Asia Minor. The cities of Phrygia, Galatia, Mysia, Bithynia and Troas are all in Asia Minor. In the beginning of Acts, chapter 16, Paul was already in “Asia” (Turkey) with the decree from Jerusalem. He had picked up Timothy in Lystra and continued in verse 4 to spread the news in southern Turkey. However, once Paul got to Phrygia (verse 6), the holy spirit kept him from preaching. So Paul and his companions moved on again and again until it was revealed to him in a vision in Troas that he was urgently needed in Macedonia (northern Greece). We believe that this was the main reason God forbade Paul from preaching in Asia Minor. It soon became clear to Paul and his companions that they would not have been where they needed to be had they lingered in Galatia any longer. Therefore, verse 6 is less about God forbidding Paul to preach in Asia and more about Paul’s trusting God’s divine timing.

The last part I believe sheds the most light on the subject. I am sure once they would have started preaching, it would have been almost impossible to quickly pick up and leave to Macedonia which is where God wanted them. The Holy Spirit in tune with the plan from God directed them accordingly