"The Pharisees heard the crowd murmuring these things concerning Him, and the Pharisees and the chief priests sent officers to take Him. Then Jesus said to them, 'I shall be with you a little while longer, and then I go to Him who sent Me. You will seek Me and not find Me, and where I am you cannot come.' Then the Jews said among themselves, 'Where does He intend to go that we shall not find Him? Does He intend to go to the Dispersion among the Greeks and teach the Greeks? What is this thing that He said, "You will seek Me and not find Me, and where I am you cannot come"?'"
The religious authorities knew that some people were wondering why they weren't doing anything about Jesus teaching in the temple and that some were speculating that perhaps the leaders now believed Jesus to be the Messiah. They also knew that this rumor would spread rapidly if they didn't act quickly to counteract it. So, "officers" were sent to arrest Jesus. These men were probably Levites who had the responsibility of keeping order in the temple area.
"I shall be with you a little while longer, and then I go to Him who sent Me" (John 7:33). Jesus would be with them approximately six more months before He would be arrested and crucified. Afterward, He would be resurrected and would return to the Father in heaven.
"You will seek Me and not find Me, and where I am you cannot come" (John 7:34). There would come a time when tragedy would fall upon the Jewish nation (i.e., the destruction of Jerusalem in A.D. 70) and the Jews would vainly seek for a Messiah to deliver them--for the Christ whom they had failed to recognize in Jesus. They would not be able to find Jesus nor go where He was because they were of this world and lacking in faith (cf. 8:22-24).
"Then the Jews said among themselves, 'Where does He intend to go that we shall not find Him? Does He intend to go to the Dispersion among the Greeks and teach the Greeks?" (John 7:35). Most scholars believe that the Jews understood what Jesus was talking about but pretended not to because they didn't accept what He was teaching (i.e., the fact that He was going to go to the Father but they couldn't). Thus, their only response is an attempt to turn Jesus' words into nonsense. They certainly assumed that if Jesus actually did what they proposed, then He could not have been the Messiah.
Ironically, what they stated mockingly was prophetic of what actually happened through the preaching efforts of Paul and others (cf. Eph. 2:17). Jesus would in fact indirectly preach to the Jews who had been scattered during the captivity (and never returned) as well as the Gentiles (cf. Matt. 28:19,20; Rom. 1:16; Gal. 3:28,29).
Their repeating of Jesus' words in John 7:36 can mean only one of two things: (1) either they truly didn't understand what Jesus was talking about or (2) they are mocking Him.