Ousmane Dembele struck on four minutes as PSG won the first-leg of their Champions League semifinal 1-0 in London on Tuesday.
Afterwards, Saliba told Canal+: "We're a little disappointed to have lost this first match. We suffered a lot in the first 20 minutes. We were much better after that, we could have scored.
"In the second, we played better, we had chances. It's not over, there will be a match at the Parc, we hope to win there.
"We have to take the positives, it's only 1-0, we mustn't give up, we know that in the Champions League a lot of things can happen."
On Dembele, Saliba also admitted: "He's a bit everywhere. He drops back, he goes deep, he turns a lot, it's difficult to mark a player like that. We can do better on the first goal. We'll look, see what we didn't do well and improve that for the return match."