Diaby, whose career has been hampered by injuries and had not played for Les Bleus since June last year, netted with a cross shot from Karim Benzema's through pass in the 20th minute.
"Last season was a tough one but I don't want to look behind, I prefer to move forward," said Diaby.
"We were in danger in the end but it's always the case when you fail to add a second goal," Deschamps said.
Kasper Hamalainen caught the visitors' defence off guard but Yanga-Mbiwa denied him with a fine tackle just as he was about to shoot.
Yohan Cabaye's fierce shot was parried away by Lukas Hradecky five minutes into the second half as Deschamps's side pushed hard for a second goal.
"It [Yanga-Mbiwa and Sakho] was a logical choice, and they confirmed their good performance from the previous game [a 0-0 draw against Uruguay]," said Deschamps.
"It's always harder up front. We need to be more present, although Diaby brought a lot in this area. We also need to be more spontaneous."
Lloris, who just joined Tottenham Hotspur from Olympique Lyon, once again showed his class with a quick save to deny Tim Sparv's last-gasp header.
