"Now some of them from Jerusalem said, 'Is this not He whom they seek to kill? But look, He speaks boldly, and they say nothing to Him. Do the rulers know indeed that this is truly the Christ? However, we know where this Man is from; but when the Christ comes, no one knows where He is from.' Then Jesus cried out, as He taught in the temple, saying, 'You both know Me, and you know where I am from; and I have not come of Myself, but He who sent Me is true, whom you do not know. But I know Him, for I am from Him, and He sent Me.' Therefore they sought to take Him; but no one laid a hand on Him, because His hour had not yet come. And many of the people believed in Him, and said, 'When the Christ comes, will He do more signs than these which this Man has done?'" (John 7:25-31).
Some from Jerusalem are puzzled because they are aware of the religious leaders' desire to kill Jesus, yet He is in the temple teaching and no action is being taken against Him! Perhaps some are wondering if the rulers have changed their attitude toward Christ.
"We know where this Man is from; but when the Christ comes, no one knows where He is from" (John 7:27). This statement exposes the ignorance of these Jews concerning Micah 5:2 which foretold that the Messiah would be born in Bethlehem (cf. Matt. 2:4-6; Luke 2:4-7).
John 7:28 indicates that Jesus "cried out" while in the temple. Thus far He had evidently been speaking at a normal volume. However, He now proceeds to shout out His words, apparently in order to be heard throughout the temple area so that others would be drawn near.
"You both know Me, and you know where I am from" - Jesus admits that they are familiar with Him (i.e., they know of His childhood in Nazareth and His work as a carpenter), but in spite of this, they do not really know Him (nor His physical birthplace).
"And I have not come of Myself, but He who sent Me is true, whom you do not know" - The reason why they didn't know Him is because they didn't know the Father who sent Him. The fact that they rejected Jesus is evidence that they do not know God.
Jesus continued in John 7:29 - "But I know Him, for I am from Him, and He sent Me." Jesus' relationship with the Father was genuine, but the manmade traditions of the Jews to which they were enslaved had prevented them from really knowing God as they should.
The Jews were angered and sought to lay hands on Him because they correctly understood Him to call them ignorant of God. However, no one was able to "take Him" because it was not the will of the Father that He should be arrested at this time. God must have prevented these men from moving against Jesus in either a providential or miraculous manner.
Although some were upset, "many of the people believed in Him" (John 7:31). They believed in Him because of His miracles (cf. 20:30,31), as their question implies. They couldn't see how--if Jesus wasn't the Messiah--that the Messiah could do any more or greater works than Jesus did (cf. Isa. 35:5,6).