Jonny Wilkinson says he was 'phenomenally proud' to be considered for the 2013 Lions tour Down Under but adds that his 'absolute priority' lies with his club Toulon.
Lions coach Warren Gatland telephoned Wilkinson on Monday to offer him a place on the tour of Australia, but the former England international turned down the offer.
Wilkinson delivered a masterclass at Twickenham on Sunday, kicking all the points in Toulon's Heineken Cup semi-final victory over Saracens.
But Gatland had insisted that all players must be available for the opening tour match against the Barbarians in Hong Kong on June 1, the same day as the French Top 14 final.
"It was a hugely proud moment for me to be called by Warren Gatland, to be told that they were thinking of me in this way," Wilkinson told The Times.
"I was phenomenally proud to be considered for the Lions, so it's very disappointing that I'm unavailable.
"If Toulon manage to get through to the final of the Top 14, my absolute priority lies with them and helping to get the best out of a team that has been so good to me for so long.
"It is, after all, these guys who have got me to the stage where I could even be considered for the Lions."
Wilkinson, 33, underwent a groin procedure in January, he may require another operation in the summer and he told Gatland he was physically not able to cope with a full seven-week tour.
The Lions are only taking two fly-halves and so Wilkinson would have had to be involved in most of the 10 fixtures, either in the starting side or on the bench.
But Wilkinson did not rule out taking part in his third Lions tour as an injury replacement, should anything happen to Jonathan Sexton or Owen Farrell.
"I told him where I am at the moment, that there's a bit of day-to-day management where my body is concerned," Wilkinson said.
"I'll see how I am at the end of the club season and if Warren needs me and I am able to get involved, that would be fabulous."