I believe you are quoting the NASB version of John 6:65:
And He was saying, “For this reason I have said to you, that no one can come to Me unless it has been granted him from the Father.”
This, in turn, refers back to Jesus' original statement earlier:
Therefore the Jews were grumbling about Him, because He said, “I am the bread that came down out of heaven.” They were saying, “Is not this Jesus, the son of Joseph, whose father and mother we know? How does He now say, ‘I have come down out of heaven’?” Jesus answered and said to them, “Do not grumble among yourselves. “No one can come to Me unless the Father who sent Me draws him; and I will raise him up on the last day" (John 6:41-44).
The phrasing is a little different in each of these verses. John 6:44 reads unless the Father who sent Me draws him (ἑλκύσῃ αὐτόν - elkusē auton), whereas 6:65 says unless it has been granted [to] him (δεδομένον αὐτῷ - dedomenon autō) from the Father.
Unless is perhaps not the best choice for translating ἐὰν μὴ here, though it might be the more literal option. In antiquity, these verses were not understood that there was some sort of exclusivity for those who were drawn as opposed to those who were not. Rather, it was understood to express a causal relationship: those who come to Christ, come by virtue of the Father having drawn all.
This sense is clear, for example, in the commentary of Cyril of Alexandria (378-444):
God the Father imparts the inextinguishable light of the true knowledge of the true vision of God to those who embrace the righteousness that is in Christ. He revealeth unto them the Son; as the Savior Himself also in another place said unto the Jews, Murmur not one with another; no man can come unto Me, except the Father Who sent Me draw him. But He draws, of course, by light and knowledge, and the cords of love. Yet for those who are not so disposed in will and wickedly reject Christs commandments, even that light which they had in their mind from the commandment of Moses, vanishes and is extinguished, and the darkness of ignorance usurps its place (Homily CXXXII on Luke).