Steve Sidwell and Bobby Zamora netted in the final minutes of the match to secure Fulham a 2-1 win, with the catalyst seemingly Djourou's red card for a second bookable offence 12 minutes before time.
Arsenal manager Arsene Wenger claimed after the match that the Cottagers attempted to get the Switzerland international sent off, but Riise has followed manager Martin Jol in denying the allegation, and said: "We would never do that."
Wenger suggested substitute Kerim Frei was brought on to look for a second booking, but the Norway international added: "What we do, we know people are strong like Kerim and give him the ball, make him go one against one and see what he can do.
"That's a tactic but we never go out and get people sent off. That's not fair play and we never do that. He should have been yellow carded for a tackle before that. I think he had three tackles in quite a short time. It was the right decision.
While Arsenal felt aggrieved after the match, defeat would have been cruel on Fulham after a spirited performance.
The west Londoners rode a first-half storm and impressed onlookers after the break with their swashbuckling attacking style.
"The team spirit is very high," left-back Riise said. "We played OK in the first half as well and had a few chances but gave them too much space on the counter attack but in the second half we decided to be more compact.
"We knew fitness would play a part in the game. We have a fit squad and we like to work hard and we proved in the second half that we were a little bit stronger at the end."