Hansi Flick's side were unbeaten until facing European champions PSG on October 20, but lost 4-2 in Paris before a 2-1 Clasico defeat at home on October 25 by Madrid.
Spanish title holders Barcelona last won the Champions League in 2015, and questions remain about their ability on the biggest occasions.
"I don't think they're above (us). We have to take responsibility for both losses because they're the two biggest games we played so far this season and we lost, but I don't think they're above us," Gordon told reporters.
"I think we're a fantastic team and on any given day we can beat anybody. In these two games, the PSG game has a bit of context... on the weekend in their league they rested their whole team.
"We didn't have this privilege, so we were really tired in the game. This is normal, fine, we have to take responsibility, but I think they had a massive advantage with this."
Gordon said his team deserved to win the Clasico, which Real Madrid claimed with a late goal from Kylian Mbappe as Barca's defence crumbled.
"Madrid is the one game, the most important game we want to win. For me, we should have," continued Gordon.
"For me were there much better team in the game, we had all the ball, all the possession, the better chances, but we were a slight bit off our best game. It cost us in the end; we conceded two very bad goals.
"Against this kind of opposition and this level of player, it can really hurt you in these games. We'll learn for next time, and I'm really excited to play these types of teams again to show what we can do."
Barca host Premier League side Aston Villa on Tuesday as they aim to get back on track in the Champions League, before visiting Atletico Madrid on Sunday in La Liga.
"I'm always motivated the same... the fact they're English doesn't make it more motivating for me," said Gordon ahead of Villa's visit to Camp Nou.
"They're a very good team... they have a great coach (Unai Emery), one of the best in the world... it's going to be a very difficult game."
Villa hold a 100% record so far in the Champions League, defeating Viking, Fenerbahce and Club Brugge.
Barcelona signed Gordon from Newcastle in the summer for a fee which could rise to 80 million euros.
The 25-year-old has three goals and five assists in 13 appearances for Barcelona across all competitions, but said his best is yet to come.
"It's a big change, a new team, it's been a massive change for me and my family," added Gordon.
"I've started well but like I've said numerous times, I can do more. It will take some time to grow, feel settled, and then when this happens I think you'll see the very best of me, which you definitely haven't seen so far."
