Despite three fewer days of preparation, the Eagles dominated the opening half-hour and deserved their 1-0 lead through Maxence Lacroix’s early header.
However, Lacroix’s controversial dismissal and a resulting United penalty allowed the hosts to overturn the score.
Richards acknowledged the frustration but stressed that Palace should take positives from their performance and remain confident as they focus on upcoming challenges.
“It’s a tough one. I think it was a game of ups and downs,” he told Palace TV
“In the first-half we were riding that wave. After the goal I think we did well until probably the last 10 or 15 minutes. We wanted to get to half-time with the 1-0.
“The second-half started off a bit hectic, and the red card happened. They got a lot of momentum.
“But honestly I think we ended the game pretty well. That’s pretty much how the cookie crumbled today.
“Overall, they’re still a good side and I think we can take a lot of positives from the game. At this point, we’ve got to keep looking forward.
“We still have a lot of big games coming up this season, so I don’t think we should let ourselves get too down after a result like today.”