PSG had been unbeaten in their opening 20 Ligue 1 matches this season, but that run was ended on Sunday as Moussa Dembele and Nabil Fekir cancelled out Angel Di Maria's opener.
With a last-16 Champions League meeting against a rejuvenated United just over a week away, Silva was concerned by his side's performance, although he expects to see an improved display at Old Trafford.
"Solskjaer must be happy with what he saw," Silva said. "We started the game well, but then we lost our concentration and did not have a good first half.
"For me, too, it was difficult. The second half was better but that was not enough. We missed a lot of things. We need to be more focused when we do not have the ball, for example.
2015 - Paris have lost a Ligue 1 game after scoring the opening goal for the 1st time since January 2015 against Bastia (2-4). Shake. pic.twitter.com/5MqVYGL4UX— OptaJean (@OptaJean) February 3, 2019
"But do not be worried about us. Next Tuesday, in Manchester, it will be another competition, another environment, another atmosphere. In the meantime, we have to work between us to show something else.
"We will be facing a great team. Manchester United are on a run of nine wins in 10 games."
PSG's hopes in the two-leg affair against United have been hit by injuries to Marco Verratti and Neymar, but new signing Leandro Paredes debuted at Lyon.