CAF have re-opened their registration period to allow clubs who have registered less than the maximum of 30 players to add their list prior to the group stages.
However local clubs including Sundowns, SuperSport United and Platinum Stars are facing challenges with registration of new players as the domestic transfer window only opens on July 1.
CAF rules prohibit a club from registering a player for continental competition that is not registered with the local federation – in this case, the PSL.
Mosimane bemoans that he will now only be able to register defenders Motjeka Madisha and Farres Hachi to strengthen their squad ahead of the group stages, which begin this weekend.
"Now the transfer [registration period] is open for CAF to sign [register] players. I want to sign a player in South Africa, [but] how do I sign him?" quizzed 'Jingles'.
"But other people have advantages, the whole of Africa has an advantage to sign players. They are signing now, everybody is signing.
"The only person I can sign [register] is Fares and Madisha, but I can't sign [new players]. They [other African clubs] are buying but when is their transfer date? If FIFA allows other countries now, why can't I sign?"
Mosimane raised his concern over some African countries signing and registering new players ahead of the group stages, pointing to group opponents Saint George as an example, and remained perturbed by his ineligibility to do the same.
"I don't want to say it's a South African or CAF, or FIFA [issue]. I am saying it's a disadvantage for me. I want to sign players, I want to strengthen the team for [CAF] Champions League," he added.
"The Ethiopians [Saint George] are signing players, I am looking there, I am watching, people are signing and strengthening their teams.
"But when I play here [domestically] I don't have players. I don't sign anybody so I play with a weak team, but the transfer [period] is open [elsewhere] but [here] it is closed."
The former Bafana Bafana mentor has pleaded with the media to raise concerns with local football authorities to consider changing the calendar of the domestic league.
"You ask them [why they are not changing]," added Mosimane. "That's your [media's] job, guys, to educate South Africa, to say 'excuse me PSL, excuse me SAFA, do you see the teams [struggling]?'
"It's not only Sundowns but also SuperSport United and Platinum Stars. Our teams are at a disadvantage at this point in time.
"And you know, I want to strengthen the team, and I told you I want to strengthen the team, but now how can a player play for both teams?
"Let's say I buy a player from Maritzburg United, and they will say how can I give you my player to play Champions League and the player cannot play for two teams in the same calendar year?
"You will never find that in Europe. You will never find that in Asia, but our beloved continent... here we go."