The Nottingham Forest midfielder could be permitted to undergo his medical once England have played Panama on Saturday, with a further window potentially opening up before any knockout fixtures.
The fee would represent both a British transfer record and a new club record for Manchester City. Anderson is set to sign a five-year deal with a one-year extension option.
Tuchel spoke openly about the club's approach to in-tournament transfers.
"There has to be common sense," Tuchel said. "I would not like it on a minus-one and a match day. That's the policy. And everything else, if it is quietly done, privately done, done efficiently, we are always happy to help to have clarity around the player.
"I think the best we can have is clarity. If anyone has the chance to complete a change of club and a transfer, we will not stand in the way but it has to align of course with our schedule and our goals which is to be focused and prepare for matches. The last day before the match for sure and the second day before a match, not. Let's see. We take it case by case. Until now, no player approached me. The doctor is ready to take any medical if needed."
Anderson had been a target for Manchester United as well as City, but made his preferred destination clear to Tuchel, who was reassured the transfer would not become a distraction during the tournament.
England teammate Jarell Quansah, of Bayer Leverkusen, also backed the 23-year-old to remain focused on the World Cup.
"I see a player that's fully focused on what he wants, and I think at the moment what he wants is to win a World Cup," Quansah said. "That ultimately is the goal. I'm sure he is fully focused on winning the World Cup for England, and you can't drift too far away from that and he knows that. But he's a proper focused young lad and he'll go right to the top I think."