Was it wrong for the Jews in Acts 3 to keep the message only for the Jewish people?
No, it was not wrong, because God was still dealing with the nation of Israel under the Old Testament program. The Jews in Jerusalem had not yet heard the Gospel of Grace and had not comprehended that the death, burial, and resurrection of their Messiah was intended for the Gentile world.
Les explains that as we come out of Acts chapter 2 and into chapter 3, nothing has changed; it is still an extension of the Old Testament program. The Jews in Jerusalem had not yet heard the Gospel of Grace as we know it, and they had not comprehended that the death, burial, and resurrection of their Messiah was now intended to go out to the Gentile world. So they were still properly and correctly confining the message only to the Jew, and God was having them do just that. Peter and John went up to the temple, not a church, because the temple had not been closed down and they were still practicing the Law. Gentiles are not even mentioned in Peter's admonition to the men of Israel. Therefore, keeping the message only for the Jewish people was not wrong at that time; it was the proper order under the Old Testament program.