Chelsea face Leicester in their last domestic game on Sunday and play New England Revolution three days later on 15 May.
The match has been arranged to raise funds for anti-discrimination.
“We have to recover energy because we are really very tired,” Sarri said.
“Unfortunately we have to go to the United States, I think in this moment we need to rest then we have 10 days to prepare for the final.”
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The friendly has been scheduled since March and is billed as an anti-discrimination game called ‘Final Whistle on Hate’, which was set-up by club owners Roman Abramovich and Robert Kraft.
However, Sarri’s frustration over the fitness of his players prompted his concern with midfielder N’Golo Kante absent from the club’s semi-final victory over Eintracht Frankfurt with a hamstring complaint.
While Andreas Christensen and Ruben Loftus-Cheek both suffered injuries resulting in them being substituted before the penalty shootout.
Belgium forward Eden Hazard scored the winning penalty in what may have been his final appearance at Stamford Bridge after again being linked to a move to Real Madrid this summer.
Asked whether this might have been his last appearance in west London, the 28-year-old told BT Sport: “I don’t think about that. I’m only thinking about winning something for this club and this squad.
“If it’s my last game I will try to do everything for this club to win a trophy. In my mind I don’t know yet [if it will be his last game].”