We could not find this report with any reliable isnad (chain of transmission), and we did not find it in the books of Sunnah (prophetic teachings) and reports. Rather we saw it in some books of raqaiq (heart softening reports) and exhortation, without mentioning any isnad or reliable source.  

Ibn Muflih al-Maqdisi (may Allah have mercy on him) said:

“Moosa (peace be upon him) said: ‘O Lord, the people are saying things about me that are not true.’ And Allah revealed to him: ‘O Moosa, I have not granted that to Myself, so how could I grant it to you?’” End quote. 

Al-Adab al-Shar‘iyyah, 1/7-8; there is a similar report in Qoot al-Quloob by Abu Talib al-Makki, 2/309; Siraj al-Mulook by Abu Bakr al-Tartooshi (229).  

Although we cannot prove it because we could not find any isnad for it, there does not appear to be anything wrong with its meaning, because Allah did not decree -- in any of the universal natural laws that He decreed -- that none of His creation would overstep the mark towards Him or that any human could ever deal with their Lord in a way that is not befitting to His Majesty and Might; rather He has told us of people who fell short in this regard and did not estimate Him with an estimation due to Him, as He says (interpretation of the meaning):

“They (the Jews, Quraysh pagans, idolaters) did not estimate Allah with an estimation due to Him when they said: ‘Nothing did Allah send down to any human being (by Revelation).’ Say (O Muhammad – peace and blessings of Allah be upon him): “Who then sent down the Book which Moosa (Moses) brought, a light and a guidance to mankind which you (the Jews) have made into (separate) paper sheets, disclosing (some of it) and concealing (much). And you (believers in Allah and His Messenger Muhammad (peace and blessings of Allah be upon him) were taught (through the Quran) that which neither you nor your fathers knew.” Say: “Allah (sent it down).” Then leave them to play in their vain discussions.”

[al-An‘am 6:91] 

“They have not estimated Allah His Rightful Estimate. Verily, Allah is All‑Strong, All‑Mighty.”

[al-Hajj 22:74] 

“They made not a just estimate of Allah such as is due to Him. And on the Day of Resurrection the whole of the earth will be grasped by His Hand and the heavens will be rolled up in His Right Hand. Glorified be He, and High be He above all that they associate as partners with Him!”

[al-Zumar 39:67]. 

The Prophet (peace and blessings of Allah be upon him) said: “No one is more patient in bearing offensive things that he hears than Allah, may He be glorified and exalted; others are associated with Him, a son is attributed to Him, but He still grants them health and provision.” Narrated by al-Bukhari (7378) and Muslim (2804). 

What we learn from this is that the criticism of the envious and the slander of those with ulterior motives is not a reason for a Muslim to be discouraged from trying hard to succeed and progress, or to weaken his resolve or cause him to become frustrated. He should always remember that Allah, may He be glorified and exalted, the Angels, the Messengers and the Prophets were never safe from slander and harm. 

And Allah knows best.