Rijkaard claims Ronaldinho's no Diver
The Catalan side tried everything to break down the Malaga defence but could not find the breakthrough until 10 minutes from time when Ronaldinho fell to the floor under a challenge in the penalty area and referee Evaristo Puentes Leira pointed to the spot.
Television replays seemed to indicate there had been no contact.
Substitute Henrik Larsson wrapped up a 2-0 win with a late goal but there was no doubt that the penalty had changed the course of the match.
Rijkaard said: "I believe we gave a good account of ourselves tonight. The team has been very focused and fought until the end.
"I do not think Ronaldinho threw himself to the floor because it is against our style to try and fool the referee and when you are unbalanced and running at speed it is normal to fall over."
Malaga coach Antonio Tapia refused to blame the referee for the defeat.
"I have a lot of respect for the work of referees and they are human so that mistakes can happen and now I hope that an error of this type can fall in our favour in forthcoming matches," said Tapia.
"It is natural that after a match like that you walk away feeling empty having gained nothing from so much effort."