It is impossible for any human being to see Allah (S.W.T) in this world, as Allah has said in many verses of the Qur'an:
‘No vision can grasp Him, but His grasp is over all vision. He is the Most Courteous Well-Acquainted with all things.’ (6.103)
‘It is not fitting for a human being that Allah should speak to him except by inspiration or from behind a veil.’ (42.51)
“There is nothing like Him, and He is the All-Hearer, the All-Seer”
[al-Shoora 42:11]
Narrated Masruq:
‘Aisha said, "If anyone tells you that Muhammad has seen his Lord, HE IS A LIAR, FOR ALLAH SAYS: ‘No vision can grasp Him.’ (6.103) And if anyone tells you that Muhammad has seen the Unseen, he is a liar, for Allah says: ‘None has the knowledge of the Unseen but Allah.’" (Sahih al-Bukhari, Volume 9, Book 93, Number 477)
It is narrated on the authority of Masruq that he said: I was resting at (the house of) 'A'isha that she said: O Abu 'A'isha (kunya of Masruq), there are three things, and he who affirmed even one of them fabricated the greatest lie against Allah. I asked what they were. She said: He who presumed that Muhammad (may peace be upon him) saw his Lord (with his ocular vision) fabricated the greatest lie against Allah. I was reclining but then sat up and said: Mother of the Faithful, wait a bit and do not be in a haste. Has not Allah (Mighty and Majestic) said: "And truly he saw him on the clear horizon" (al-Qur'an, l*!*!*!i. 23) and "he saw Him in another descent" (al-Qur'an, liii. 13)? She said: I am the first of this Ummah who asked the Messenger of Allah (may peace be upon him) about it, and he said: Verily he is Gabriel. I have never seen him in his original form in which he was created except on those two occasions (to which these verses refer); I saw him descending from the heaven and filling (the space) from the sky to the earth with the greatness of his bodily structure. She said: Have you not heard Allah saying: "Eyes comprehend Him not, but He comprehends (all) vision. And He is Subtle, and All-Aware" (al-Qur'an, vi. 103)? (She, i. e. 'A'isha, further said): Have you not heard that, verily, Allah says: "And it is not vouchsafed to a human being that Allah should speak unto him otherwise than by revelation, or from behind a veil, or that He sendeth a messenger (angel), so that he revealeth whatsoever He wills. Verily He is Exalted, Wise" (al-Qur'an, xlii. 51) She said: He who presumes that the Messenger of Allah (may peace be upon him) concealed anything from the Book, of Allah fabricates the greatest lie against Allah. Allah says: "O Messenger! Deliver that which has been revealed to thee from thy Lord, and if thou do (it) not, thou hast not delivered His message" (al-Qur'an, v. 67). She said: He who presumes that he would inform about what was going to happen tomorrow fabricates the greatest lie against Allah. And Allah says: "Say thou (Muhammad): None in the heavens and the earth knoweth the unseen save Allah" (al-Qur'an, xxvii. 65). (Sahih Muslim, Book 001, Number 0337)
The Quran also says that no one can see Allah:
Such is GOD your Lord, there is no god except He, the Creator of all things. You shall worship Him alone. He is in control of all things. No visions can encompass Him, but He encompasses all visions. He is the Compassionate, the Cognizant. S. 6:102-103 Khalifa
It is not fitting for a man that God should speak to him EXCEPT by inspiration, or from behind a veil, or by the sending of a messenger to reveal, with God’s permission, what God wills: for He is Most High, Most Wise. S. 42:51 Y. Ali
‘Aa’ishah (may Allaah be pleased with her) was asked about that and she said that no one will see Him in this world, because seeing Allaah in Paradise is the greatest blessing for the Muslims, so that will happen only to the people of Paradise and the believers in the Hereafter, and to the believers in the place of standing on the Day of Resurrection. This world is the abode of trial and testing, the place shared by both good and evil people, so it is not the place for seeing Allaah, for seeing Him is the greatest blessing, so Allaah has saved it for His believing slaves in the abode of honour on the Day of Resurrection.
Therefore it is clear that no human shall see Allah (S.W.T) in this world, whether it's in a dream or when they are awake.