City are guaranteed second spot in Group C behind Barcelona and a place in the knockout stages irrespective of what happens in the final round of fixtures and Guardiola said he would make a late call on whether Aguero would feature.
The Argentina international was sent off for a two-footed lunge on David Luiz during his team's 3-1 defeat by Chelsea in the Premier League on Saturday and has been banned for four domestic matches.
"There will be changes," Guardiola told a news conference on Monday. "I am happy to give minutes to players who deserve it. Whether Sergio will play, I will decide today or tomorrow."
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Aguero's team mate Fernandinho was also sent off for his part in the melee that followed the tackle on Luiz, with the Brazilian midfielder getting a three-match ban.
Both players are available for selection in the Champions League.
"We are going to accept the ban from the Football Association and work with other players for the games," Guardiola added.
"I like all the players to play. I want to involve all the players. When we play every three days, the players must be rotated."
City came from behind three times to secure a 3-3 draw at Celtic when the sides met in Glasgow in September, and the Spaniard is anticipating another tough game against the Scottish champions at the Etihad Stadium.
"In Glasgow, they played so aggressive. They are a real good team and it will be a good test for us," he said.
(Reporting by Simon Jennings in Bengaluru, editing by Ed Osmond)
