Marmoush, 26, picked up the knock just four minutes into Egypt's 0-0 World Cup qualifier against Burkina Faso on Tuesday, and he has been ruled out of Sunday's Manchester derby.
"Omar is injured from Egypt," Guardiola said at a pre-match press conference. "Not yet—he has to have the last tests. A few weeks, I think, before the next international break he will be ready."
Guardiola's remarks leave Marmoush's availability for Egypt's final Group A qualifiers uncertain. The Pharaohs are at the top of their group with 20 points and need only one point from their last two games to secure a spot at the 2026 World Cup.
City, currently 13th in the Premier League after three games, also has fitness concerns over Rayan Aït-Nouri, Rayan Cherki, and John Stones ahead of their match against United at the Etihad Stadium.
Marmoush joined City from Eintracht Frankfurt in January for £59 million and has scored eight goals in 28 appearances for the club.
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