The forgiveness of Christ is immensely far-reaching. With regard to that particular prayer he made to the Father, whilst hanging in agony, in the process of dying, it staggers us nearly two thousand years later.
The question is whether those ones Jesus asked to be forgiven were the Jews Peter spoke of in Acts 3:17. The speech Peter gave took place in the Temple in Jerusalem, in Solomon's porch. First, he addressed them as "Men of Israel" (verse 12) and then as Brothers" (in the verse asked about). As a Jew himself, he would naturally address fellow-Jews as men of Israel, and brothers. These were Jews who had witnessed the miracle of Peter healing a man who had been lame from birth.
But the definitive statement that identifies those ones is in verse 14. He says they are those who denied Jesus Christ to be the Holy One, the Just. Instead, they demanded a murderer be released so that Jesus would have to be crucified. Peter identifies the crowd as having acted in ignorance, as did their Roman rulers who alone had the power to order crucifixions. As Jesus' prayer was for forgiveness for all who acted in ignorance regarding his crucifixion, then that would agree with Peter's speech in Acts 3 - all the Jews at that time, and the Roman rulers, and the soldiers. All those ones acted in ignorance.
This is substantiated by the apostle Paul's later statement in 1 Corinthians chapter 2 where he reminds the Corinthian Christians that when he first came to them, it was to preach Christ crucified. He then explains that "the rulers of this age" (or, "princes of this age" A.V.) could not know the wisdom of God in Christ being crucified, "For had they known it, they would not have crucified the Lord of glory" (vs. 8).
This was the mystery of God, until the Holy Spirit revealed it by raising Christ from the dead (vs. 7). This deep, spiritual truth could not be comprehended until after Christ had been raised, so that all who were involved in his crucifixion were acting in ignorance. This means that the Jewish people of that time, their Roman rulers, and the soldiers, were incorporated into Jesus' prayer for forgiveness from the cross. They did not know who this Jesus was; that he was the Lord of Glory. It's worth pondering the extent of this prayer for forgiveness when we realise that Jesus' death 'covered' far, far more people than just the ones present at his crucifixion! But that's another question.
Paul further explained, "But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him; neither can he know them, because they are spiritually discerned" (vs. 14). In Acts chapter 2 Peter urged that crowd of Jews and Gentile proselytes to grasp that they were witnessing the fulfilment of Joel's prophecy about the Spirit of God being poured out. When they repented and put their faith in the risen Christ, they too received the Holy Spirit. They stopped being 'natural' and became 'spiritual'. Then they understood! They were no longer ignorant, but acting with Spirit-filled faith!
When you ask, "Was Jesus referring to the Jews that Peter was talking about in Acts 3:17?" that's back-to-front because Peter had not yet made that statement in Acts 3:17. Jesus could not refer to something that had not yet been said. However, Peter knew what Jesus had said little more than 50 days earlier in his prayer for forgiveness for the ignorant people who had crucified him. Therefore, Peter was referring to both the Jews at that time, the Roman rulers and the soldiers who Jesus had prayed for while on the cross. But, given that he was only addressing Jewish people in Acts 3:17, he was specifically identifying them as needing forgiveness.