The 11-time Grand Slam winner lost 6-7 (9-11) 6-4 6-4 2-6 6-4 in the second round to world number 100 Rosol.
Nadal, 26, had gone into the tournament on the back of winning a seventh French Open title, and he said: "You win, you lose. The last four months were probably the best of my career.
"I just played an inspired opponent."
After Rosol had moved into a 2-1 lead, Nadal appeared to have regained control of the match when he won the fourth set to take the contest to a decider.
But a delay while the centre court roof was closed appeared to disrupt his momentum, and in the end the Spaniard succumbed to Rosol's sustained big hitting.
"For sure [the decision to close the roof] wasn't the best one for me but that's what it was and I accept it," added Nadal.
"I accept that he came back and played unbelievable in the fifth. I was playing well in the fourth set and sure the stop didn't help me, but that's the sport."
Nadal's exit was his earliest at a major since he was ousted at the same stage of Wimbledon in 2005 by Luxembourg's Gilles Muller.
Next month he will return to Wimbledon to bid for a gold medal at London 2012, and he plans to take a bit of a break from tennis before then in order to rest and recuperate.
"I feel very well mentally but physically I need to rest," he added.
"I played for the last six months almost every match possible in the tournaments that I played, so physically I need to stop a little bit."
Rafael Nadal says he is happy with his form this year, despite suffering a shock early exit at Wimbledon to an "inspired" Lukas Rosol.