Steve McClaren criticised England's lack of quality after his side were booed off Old Trafford after slumping to the first home defeat of his reign.
The under-pressure England manager admitted he could understand the jeers.
He said: 'It is disappointing to lose and I can understand the reaction. We don't like losing football matches, especially this one being the last one at Old Trafford. We finished it on a low. It was a hard game and we lost it.
'It is a huge disappointment and we can't get away from that. We didn't hear that (booing) after Holland. But the expectations were there and I can understand their reaction.'
McClaren, however, insisted it had been a difficult preparation with key players dropping out with injury.
He said: 'We came and had two days which were disrupted with players going. To be honest that is not an excuse, but a reason. We had six or seven players missing who would have been in the starting line-up.
'You are bound to lack cohesion and we did. Nobody is blinded to the fact that we lost the quality in the final third that wins football matches. Playing a good final ball let us down and we lost to a very good goal from Iniesta.
'The attitude and the effort was there. It was the quality in the final third which was missing. We started well and then started giving the ball away and you cannot give the ball away like we did.'
McClaren praised the form of Kieron Dyer and the displays of goalkeeper Ben Foster and defender Jonathan Woodgate as 'three positives' while admitting Shaun Wright-Phillips started brightly but faded.
He added: 'But there were a few performances out there not up to the usual standard. The players know that and that will be made clear.
'We lacked players who were in Holland who gave us balance and cohesion. But tonight was a building block to the future.
'We had a look at the likes of Gareth Barry and Joey Barton. There are always positives and negatives and the negative was losing the game.
'The final cross and the final pass and the final ball let us down and that is key to any football match. We started the second half better but changes came and cohesion was lost.'
McClaren revealed it had been agreed with Liverpool that captain Steven Gerrard would play just 45 minutes because he 'had a little niggle.'
The candid verdict of Spain coach Luis Aragones would have given McClaren something to ponder.
He said: 'We began nervously but what did surprise me was how we got two against one down England's left hand side. That gave us a few opportunities.
'It is hard to play England. They are a strong team but perhaps Spain are more technical and good on the ball. We were thinking quicker as footballers. That was one of the main things between the sides.
'The performance was no different to that against Ireland when we dominated play but got caught out. Tonight England had chances to score but we were very quick on the counter. I'm pleased Iniesta scored because we had talked about getting midfielders forward quickly into attacking positions.'