The Black Stars conceded twice as the Indomitable Lions recorded a 2-0 victory in Franceville on Thursday.
Michael Ngadeu-Ngadjui opened the scoring when John Boye made a hash of a free-kick clearance, with goalkeeper Razak Brimah having also misread, before Christian Bassogog elegantly slotted home on 90 minutes following a neat counter-break.
"We are very disappointed because I think we couldn't play our game," Ayew said.
"We didn't manage to do what we do best.
"We have to be honest, Cameroon deserved the victory.
"We didn't do what we had to do, so we are very disappointed; there's not much to say.
"We just need to shut up, go home, work and prepare for the next two years."
Ghana's wait for a fifth continental title, thus, continues - at least for the next two years.
The Black Stars have now made it six semi-finals on the bounce, without any luck of claiming the ultimate.
Their campaign in Equatorial Guinea, two years ago, ended in a final defeat to Cote d'Ivoire.
Cameroon, hosts of the next Afcon in 2019, will face Egypt in Sunday's final in Libreville.