Wingers Topsy Ojo and Sailosi Tagicakibau plundered tries in each half for the exiles but Toulouse’s vast European experience ultimately proved decisive.
Irish, playing in the tournament’s knockout stages for the first time, surpassed all expectations to reach the semis and Booth vowed they would be back.
“It’s been a great journey and we want to replicate this season as often as possible,” he said.
“But we do feel this was a missed opportunity today. We got ourselves into scoring positions and could have nicked it at the end.
“To out-Toulouse Toulouse the way we did in the second half takes some doing,” Booth claims.
“It’s our time now and we are committed to getting this team to fulfil its potential. This side will play rugby and we will stay true to those values.”
Toulouse crossed though Manu Ahotaeiloa and William Servat while Jean-Baptiste Elissalde contributed 11 points, but the three-times champions were subjected to a nervy finale.
Irish director of rugby Brian Smith said: “We’re very proud of the players’ efforts.
“There’s a sinking feeling in the pits of our stomachs but we’re so proud of our endeavour and the way we never gave up.
“It shows this team has massive character and ambition. But for the bobble of the ball we could have won the game.”
Ojo landed the man of the match award and capped an impressive display with a magnificent solo try, prompting Smith to promote his England claims.
“Last week Topsy scored a good try but today was a better one,” he said.
“If England are taking three or four wingers to New Zealand they need try scorers and on his recent performances Topsy must to be considered.
Ojo, a threat all afternoon, hopes he displayed the x-factor demanded by England and the lightening-quick winger wants is to be recognised by Martin Johnson’s England.
Ojo, who toured South Africa last summer but failed to make his Test debut, hopes his Heineken Cup heroics have landed him a place on the plane for New Zealand in June.
“I’m happy with the way things went against Toulouse. I think I’m ready for international rugby but all I can do is keep playing well.
“It’s occasions like Heineken Cup semi-finals that get players noticed.”
Irish captain Bob Casey insisted his side were capable of snatching victory right until the final whistle but paid tribute to Toulouse’s resilience.
“It came down to the bobble of the ball. We felt only one team was going to win it and that we could break them in the end,” he said.
“That’s a credit to Toulouse – maybe that little bit of experience they have might have told. It will take a good side to beat them.
“But we were still going right until the end on a hot day and in a fast game. We will bounce back from this.”
London Irish scorers: Tries: Ojo, Tagicakibau. Cons: Hewat. Pens: Hewat.
Hewat, Ojo, Richards, Mapusua, Tagicakibau, Geraghty, Hodgson, D. Murphy, Paice, Rautembach, Kennedy, Casey, Danaher, S. Armitage, P. Murphy.
Lea’aetoa for D. Murphy (40), Leguizamon for P. Murphy (56).
Tries: Ahotaeiloa, Servat. Cons: Elissalde. Pens: Elissalde 3.
Heymans, Medard, Ahotaeiloa, Jauzion, Donguy, Elissalde, Kelleher, Human, Servat, Perugini, Pelous, Albacete, Bouihlou, Nyanga, Sowerby. Replacements: Hasan for Perugini (68), Millochlusky for Pelous (68), Lamboley for Bouihlou (74), Dusatoir for Nyanga (60).
Alan Lewis (Ireland).