Rangnick stated this on Thursday night after Ronaldo netted the equalizer in the 1-1 draw with Chelsea at Old Trafford.
The 63-year-old is set to take up a consultancy role at United next season when his short-term deal expires.
Rangnick has now admitted the future of Ronaldo, 37, remains up in the air.
“We will have to speak about it between us; with Erik [ten Hag], myself and the board.
“Cristiano has another year of contract and it’s also important to see and find out what Cristiano wants to do and see if he wants to stay.
“I haven’t been able to speak with Erik so far and it doesn’t make sense to speak about it [Ronaldo’ future] right now,” Rangnick said.