The Portuguese has taken a swipe at Iker Casillas by suggesting that he should have been replaced at an earlier stage and also took the time to praise Barcelona
The 31-year-old joined Madrid from Sevilla in the January transfer window to replace the injured Iker Casillas and has since made the spot between the sticks his own.
Mourinho has now made it clear that head had already set his sights on Lopez before, but eventually decided not to bring him in, a decision the Portuguese now regrets.
"Would I do anything differently if I had the chance to do the past three years over again? I should have brought in Diego Lopez after my first year. We didn't do enough to sign him. It's a real shame," Mourinho said at a press conference.
The Madrid coach then went on to discuss his future at Madrid and insisted that he has not made a final decision yet.
"I can only confirm that I will sit down with the president and Jose Angel Sanchez at the end of the season.
"You look around you and it seems that everybody is moving. There's Carlo [Ancelotti] at PSG, Bayern are changing coaches, Manchester City, Chelsea, there's speculation everywhere. Some changes will happen and others are just rumours..."
Mourinho also had his say on Barcelona's performances in recent years and labelled them the best team of the past 20-30 years.
"It's an honour to have broken the dominance of Barcelona at national level. On international level, I did it with Inter. They're still a fantastic team, probably the best of the last 20 - 30 years.
"Now they've had a couple of bad, surprising results and have become a bad team in the eyes of many..."
The coach was also questioned about Cristiano Ronaldo's future at the club and insisted that he hopes his compatriot will stay put for many more years to come.
"I hope that Cristiano and Madrid stay together for a long time. He has to think about himself and the club. He was not happy earlier this season, but he is now. He is 100 per cent focused on Madrid."