Pablo Zabaleta hit the crossbar with a first-half header while QPR goalkeeper Julio Cesar produced a number of top quality saves to give the bottom club what could prove a valuable point as they strive to avoid relegation.
Mancini, who revealed striker Mario Balotelli is closing in on a move to AC Milan, blamed his side's inability to provide the finishing touches to their play as the reason behind the dropped points.
"We lost two points, this is sure," he said. "But the season is long and I think I can say nothing because we played well, we had the chances but didn't score -- that is all it is.
"We are disappointed with this result because we had a lot of chances to win, we dominated this game but when you play like this and don't score quickly it can be difficult.
"QPR defended very well and got players behind the ball and Julio Cesar was incredible."
The point left QPR four from safety and still bottom of the Premier League, but manager Harry Redknapp praised the endeavour of his players.
"I would have thought against the league champions I would be happy with a point," he said.
"We defended fantastically all over the park, everybody worked again and it was another solid performance and another clean sheet -- another big point for us.
"Everybody worked and did their jobs and you can't ask for any more than that.
"They have been excellent and the attitude has been good. We are working hard and if you work hard you get your rewards and that is what we are doing at the moment.
Redknapp revealed chairman Tony Fernandes is working hard to seal several transfers before tomorrow's deadline with Anzhi defender Christopher Samba and Stoke striker Peter Crouch heavily linked to the club.