Dubbed 'the final before the final', the match at the Parc des Princes in Paris will feature the three-times world champions U.S. against the tournament hosts, who they have not beaten in their last three encounters.
Diacre, however, said her players would certainly not get carried away by the occasion.
"I'd rather stay focused on our mission," Diacre told a news conference on Thursday.
"Excitement can be dangerous, especially if it's not controlled. We cannot waste energy."
American defender Ali Krieger said the U.S. reserve team could also win the tournament, but Diacre said her players would not use their opponents' over-confidence as an extra motivation.
"If there's one area I don't really need to work on, it's motivation," said Diacre.
"The only pressure we have is to play a good game."
France captain Amandine Henry said they would look to impose themselves on the U.S.
"They will not give anything, they're the title holders but we can compete and beat this team," she said.
France beat the U.S. 3-1 earlier this year, having played out a 1-1 draw in 2018 and won 3-0 in 2017.
"They have weaknesses, but like all teams. We spotted a few things and not just in that game (their 2-1 win over Spain in the last 16)," Diacre explained.
Henry, however, is well aware that none of those recent victories over the U.S. were in competitive games.
"They have the title, we don't have anything," she said.
Early focus could be key on Friday with temperatures expected to be well above 30 degrees Celsius (86°F) as a heat wave sweeps across Europe.
The U.S. have scored four goals in the opening 15 minutes of their games at this year's tournament, with France finding the back of the net three times in the first quarter hour.
Diacre said that several players, including forward Eugenie Le Sommer, had not been at their best so far in the tournament, and she is hoping her team will raise their level after struggling past Brazil in the previous round.
"For me, she (Le Sommer) is not at 100% of her potential. We know her qualities," the coach said.
"She's done a lot the past days to recuperate, like others. Even at 80%, she's essential."
(Reporting by Julien Pretot; Editing by Toby Davis)
