The French striker pulled up in the first half of the European champions' 2-0 La Liga win at Malaga and was replaced by Zlatan Ibrahimovic.
Henry's absence adds to Barca's problems up front for the Group F clash against the Ukrainians, with teenage forward Bojan Krkic sidelined and Sweden striker Ibrahimovic still recovering from a minor sprained ankle.
However, Guardiola said Spain midfielder Andres Iniesta, who is sometimes deployed in the forward line, was getting closer to full fitness after recently returning from three months out with a thigh problem.
"Andres is still not quite at 100 percent and needs a bit more time," Guardiola said.
"The reason we haven't used him more is because we are taking it step by step," he added "But he is much better and we will be using him more and more as time goes by."
Barca's Ukrainian defender Dmytro Chygrynskiy, who moved from Shakhtar Donetsk in the close season, is unable to play for the Catalans in the Champions League as Shakhtar used him in the qualifying rounds.
NEW PARTNER
Real defender Rafael Marquez said his new partner had been giving the Madrid players the inside track on Dynamo, who have former AC Milan and Chelsea striker Andriy Shevchenko back in their attacking line.
"You have to remember they are the Ukrainian champions," Chygrynskiy told Barca's website.
"Their style of play is to pressure their opponent and deny them space," he added. "They are very strong physically and very quick on the counter."
Barca are unbeaten in eight Champions League games and have conceded only two goals in the last six.
In the 1997-98 season they crashed to a 4-0 defeat by Dynamo, when Shevchenko scored a first-half hat-trick, and also lost 3-0 in Kiev that year.
Dynamo coach Valery Gazzaev said the players had been joking with Shevchenko, who has 47 Champions League goals, about his 33rd birthday, which he celebrates on Tuesday.
"But he's in good form and tomorrow he'll be in the starting lineup," Gazzaev said.
"Shevchenko is an extraordinary player and one of the best ever in the Champions League," he added. "It'll be interesting to see what we are capable of tomorrow."
‘Maybe I’ll be signed by Wrexham, who knows? English football would suit me – if an offer came, I wouldn’t think twice, I’d go immediately’ Euro 2024 cult hero reveals his UK dream
‘Managing Leeds? It was an option that appeared, but it wasn’t the right timing. I decided it wasn’t a good idea to leave the club I was at mid-season’: Premier League boss admits to turning down opportunity to replace Jesse Marsch in 2023
