The 23-year-old Argentina international is the top scorer in the latest edition of Europe's elite club competition with 11 goals, the third season in a row he has topped the chart, and he netted Barca's second in the 2009 final when they beat Saturday's opponents Manchester United 2-0 in Rome.
"I wanted to play those games too but it was also good for me," Messi said at a news conference when asked about sitting out Barca's final two La Liga matches of the campaign against Malaga and Deportivo La Coruna.
He last played on May 11 when the Catalan club clinched a third straight title at Levante.
"I had a good rest and now we go again," he said.
Messi has scored 52 times in all competitions this term, including a hat-trick against Sevilla in the Spanish Super Cup, and has also set up 19 of Barca's league goals and three in the Champions League.
His second goal against Real Madrid in the semi-final first leg at the Bernabeu was a typically brilliant run and clinical finish and United's defence will have their work cut out to contain him at Wembley.
"They (United) have a very tough defence with very experienced players who have been playing together a long time," Messi said on Monday.
"They are a great opponent, have great players and it will be a very tight game.
"The match can be decided by small details and we have to be well prepared and focused from the first minute."
Speaking at a later news conference, Barca coach Pep Guardiola said he did not think resting key players for the La Liga finale would affect their ability to perform in Saturday's final.
"I don´t think that the rhythm has eased off," he said.
"The pace is still there and they know what the final of a Champions League is.
"If they had been a month resting that would be different but it´s just a few days.
"These players are used to playing a lot of matches and then having a break and getting right back into it."
