In healing the woman who had been bleeding for many years (Mark 5:24 - 30), Jesus has an interesting reaction:
25 And a woman was there who had been subject to bleeding for twelve years. 26 She had suffered a great deal under the care of many doctors and had spent all she had, yet instead of getting better she grew worse. 27 When she heard about Jesus, she came up behind him in the crowd and touched his cloak, 28 because she thought, “If I just touch his clothes, I will be healed.” 29 Immediately her bleeding stopped and she felt in her body that she was freed from her suffering.
30 At once Jesus realized that power had gone out from him. He turned around in the crowd and asked, “Who touched my clothes?”
31 “You see the people crowding against you,” his disciples answered, “and yet you can ask, ‘Who touched me?’ ”
32 But Jesus kept looking around to see who had done it. 33 Then the woman, knowing what had happened to her, came and fell at his feet and, trembling with fear, told him the whole truth. 34 He said to her, “Daughter, your faith has healed you. Go in peace and be freed from your suffering.”
It is interesting, a miracle was performed without Jesus doing it. This seems to imply that miracles could occur without Jesus' explicit doing. If Jesus was unaware of the miracle being performed through him, who was doing the miracle?
The obvious answer is that God the Father poured out power in a way that bypassed Jesus' human consciousness. Jesus could thus empty himself of his divinity (the kenosis), and yet still perform miracles.
This would also explain the story in Acts 8, when Simon, a former magician turned new believer, asked the disciples the secret of how to perform miracles. He was even willing to pay for the privilege, a dubious practice called simony (the selling of power) ever since.
But, in seeking to perform these miracles, he was rebuked. Even if he wanted to perform these miracles for god's kingdom, it was clear he didn't realize that miracles were performed for God's glory, not his own.
Finally, Jesus is explicit that miracles are not magic tricks - they are signs that are to accompany a message. They are not to relieve suffering but rather to authenticate God's will. In Mark 2, Jesus forgives the paralytic, which incenses the Pharisees. It isn't until after the Pharisees get angry at this blasphemy (Who can forgive sins but God alone?), that Jesus performs the miracle, explcitly saying "in order that you might believe."
Miracles, are thus a sign of God's power. As such, I don't think its a stretch to say if the purpose of a miracle is to prove God's hand in a thing, that he would also be the source of it.