Federer had never previously lost in a Grand Slam final

Victory would have seen Federer become only the third man to hold all four Grand Slam titles at once, but Nadal prevailed 1-6 6-1 6-4 7-6 (7-4).

"Obviously it's a pity but I tried," said Federer.

"I can't do more than try, having this real unique opportunity that we haven't seen in such a long time in tennis."

Highlights: Nadal beats Federer to win French Open

Federer made a storming start but could not maintain that level.

"I won the first set easily and usually in a situation like that I don't let things go by," he said. "But it's a final. It's against Nadal. It's on clay.

I'm very positive for the rest of the season Roger Federer

"That makes it very difficult, more difficult maybe than in other cases. So you get back into the match and at the pivotal points I didn't play very well.

"That second set was a big turning point. If just there I can keep up with him and then put him really under big pressure, then obviously it's very different."

The Swiss star paid tribute to Nadal after the Spaniard claimed a sixth win in seven matches between the pair.

"He's a fighter and he's a grinder, and he deserves to win here," said Federer.

"He is so strong on clay and played a really good match. He is so hard to beat on this surface."

And Federer remained optimistic that he could go one step further at Roland Garros in the future.

"I was very pleased to reach a final here," he said.