The 33-year-old is enjoying another fine campaign for Barca, although his future with the Liga giants is uncertain.
Reports suggest Iniesta is the subject of bids from Chinese Super League outfits, and has admitted he will make a decision on any potential move by the end of April.
He signed a "lifetime" contract at Camp Nou earlier this season, but there is a belief that were he to leave it may not be the greatest loss given the arrival of Philippe Coutinho.
However, Lopetegui has no doubt about Iniesta's role with the national team and he believes a greater run of games has the midfielder in even better form.
"He's better than last year, with more continuity," he told El Partidazo de COPE on Monday.
"I see him great. He will be with us and he will be willing and committed, like every time he comes with the national team."
Lopetegui also played down injury concerns over Iniesta's team-mate Gerard Pique.
"He has a good knee. He only has an overload," he said. "We will have to take care of him a bit in training so he is good against Germany."
Spain face Germany on Friday before taking on Argentina four days later.