It is best not to lift scriptures away from surrounding context. The preceding verse in John 7:32 gives the immediate answer.
"32 The Pharisees heard that the people murmured such things concerning him; and the Pharisees and the chief priests sent officers to take him." (KJV)
The officers were sent to take Christ and bring Him before the Sanhedrin for questioning. But it was not yet His time (vs. 30). Again, in vs. 44 & 45 :
"44 And some of them would have taken him; but no man laid hands on him. 45 Then came the officers to the chief priests and Pharisees; and they said unto them, Why have ye not brought him?" (KJV)
The situation in chap. 7 was that the officers of the court had been sent to take Jesus for questioning. The first meaning was that they were not going to be able to take Him until it was the right time for His sacrifice at the cross.
In chap. 13, Jesus (Yeshua) was speaking with the remaining 11 apostles - Judas had already left the room - and He was telling them that they could not follow His path to the cross nor to Paradise afterwards.
But, the fuller meaning of John 7:33-34 was not directed at all unbelievers, as an unbeliever in any generation since the cross can repent and turn again to God. The second and more complete meaning was the fulfillment of when those Pharisees and scribes would search for a deliverer during the extreme distress and tribulation they were going to undergo in their soon future in the Roman-Jewish war of AD 67-70.
Pulpit commentary has this one correctly:
"Verse 34. - Ye shall seek me, and shall not find me. Many interpretations are given of this.
(1) Origen and Grotius refer it to a hostile search for him which would not be gratified; but the whole story of the arrest which follows, as well as the quotation of these words in John 13:33, prove that this was not his meaning.
(2) Augustine and others imagine penitential seeking when it would be too late. This is not justified by the connection. The limitation of the day of grace for seeking souls is not the theme of this address, and it is, save under special circumstances, no teaching of the New Testament.
(3) The ideas of Hengstenberg and others, so largely built on the great texts in Proverbs 1:28 and Amos 8:12, show that the Messiah would be sought by them when they had utterly rejected Jesus. We do not believe that a genuine search for the Lord will ever be disappointed, but a vicious and vain search may be possible when the opportunity for due approach has gone by forever. Moments, catastrophes, did arrive in their tragic history when they had passionately desired, but in vain, to see one of the days of the Son of man. The individuals who turned to him found the veil which concealed him taken away (2 Corinthians 3:16). The nation as a whole was blinded; they crucified their King, the Lord of glory; and they brought uttermost extinction on themselves as a nation. "They sought their Messiah in vain" (Weiss). Where I am - in the glory in which I dwell, and to which I belong, and to which I am now inviting you - you cannot come. "The door will be shut;" you will not "have known the day of your visitation." "How often would I have gathered you, but ye would not!" The seeking cannot be the search of penitence, but of unavailing despair. You have the opportunity now. In a little while I go, and then you will find it impossible to follow me. " Source: Biblehub
After His death, Christ ascended to the Father. His place then was at the right hand of the Father in heaven. He would not be on earth for them to seek Him as their expectations had been to have a Messiah that would reign from the throne in Jerusalem to relieve them of the Roman occupation. As that was never His purpose in coming, and their misunderstanding was so prevalent in their minds, they could not hear what He told them.
"Shall not find me - Shall not find the Messiah. He will not come, according to your expectations, to aid you. See the notes at Matthew 24." Source: Ibid.
They had rejected Him because He did not tell them what they wanted to hear. Even the disciples did not get it, as just before His ascension they asked for the same thing.
"When they therefore were come together, they asked of him, saying, Lord, wilt thou at this time restore again the kingdom to Israel?" (Acts 1:9, KJV)
The disciples / apostles did finally understand when they received the power of the Holy Spirit that the Messiah did not come to restore an earthly throne, but did come to restore the heavenly throne that Israel had rejected long ago in favor of an earthly king as the nations around them had had.
"And the Lord said unto Samuel, Hearken unto the voice of the people in all that they say unto thee: for they have not rejected thee, but they have rejected me, that I should not reign over them." (1 Sam. 8:7, KJV)
So, the immediate sense was they would not find Him until the time was right for His sacrifice. The sensus plenior was that they would not find Him in their distress during the tribulation because they sought Him for the wrong reason. Their earthly temple in Jerusalem was destroyed in AD 70 fully restoring the reign under the heavenly throne of God. And, there it forever remains (Psa. 145:13; Dan. 4:3; 7:14; 2 Pet. 1:11).
(All bold emphasis is mine.)