The Reds could be without Salah, Sadio Mane and Naby Keita after CAF decided to change the date of Afcon back to January/February following last season's showing in June/July.
While there was an issue about the possibility of Salah missing the start of the next season due to the Olympics, there is nothing the club can do now for Afcon.
"Salah must go with Egypt to Afcon — and Liverpool don't have the right to say no," Mido told the Sun.
"These are Fifa rules and they can't prevent Salah from joining the national team for any reason. If Salah doesn't want to go, then this is the only reason for not seeing him.
"All African players had this problem when we were in England. So I was happy when the 2019 Afcon was played in the summer.
"This kept the African stars away from any problem with their clubs but the Confederation of African Football decided to go back to the old schedule.
"Salah is very important, of course, to our senior national team and to the Olympic team. A player with his experience and leadership... he can make the difference.
"He will be one of the most important players in the tournament, not only for Egypt. We now know the Olympics will be held in the summer of 2021.
"So hopefully things will go normally and the season will be finished by then, and he will have the chance to play with the Olympic team."