The former Wolves wing-back signed for City on Monday.
Mahrez, now with Asian champions Al-Ahli, is Ait-Nouri's Algeria captain.
"Yeah, I spoke with Riyad - I am with him in the national team, and it was the same as Matheus (Nunes, a former team-mate at Wolves),” said Ait-Nouri.
“Riyad told me about the city, and he told me to give everything for this club - one of the biggest clubs in the world - and I will try to follow him.”
Algeria experience will help me
Ait-Nouri says his experience with Algeria will help him adjust to City's demands.
“They help me a lot, because it is a different challenge,” he stated.
“The national team give me a lot of things because as you know, the football is a bit different, but I am really proud to play with Algeria also.
“They push me every time and I receive a lot of messages on social media from Algerian fans and I’m proud to play for this shirt.”