"I'm not in favour of it," Lopetegui said on Friday.
Barcelona and Girona have signed a formal request -- made by La Liga to the Spanish Football Federation (RFEF) on Monday -- asking that the game, originally scheduled to be at Girona's Estadi Montilivi, be played at Hard Rock Stadium in Miami on January 26.
Barca boss Ernesto Valverde insists an agreement for the fixture to be moved is still "far away", even if he admitted Friday his players had discussed the issue and there is an "intention" for the match to go abroad.
In theory, the switch could favour Barca at the expense of Girona, who would be giving up the advantages of holding a fixture on home turf.
Lopetegui believes any change upsets the balance of the league.
"I think we should all play in the same conditions, on the same pitches - that's what makes the league equal."
Valverde did not miss the chance to point out that his team beat Girona 3-0 in Montilivi last season.
He also said a decisive agreement to take the match to the US is still some way off.
"We will wait to see how everything evolves," Valverde said on Friday.
"Everything is still far away. It's good that we all talk but new things come out every day.
"I have the feeling everything is still a bit up in the air. It has been discussed with the players and there is an intention (for the match to be moved). Last year it took a lot to beat them in Montilivi."
Barcelona travel to Real Sociedad on Saturday while Real Madrid are at Athletic Bilbao.
Both teams have taken nine points out of nine so far, but will have one eye on the Champions League next week, with Barca hosting PSV on Tuesday and Real also at home, to Roma, on Wednesday.
"We have a gap of three days between the two," Valverde said.
"The games are very compressed and we will have to rotate players to avoid injuries and be fresh."
Malcom is out with an ankle injury, further boosting Ousmane Dembele's chances of a start after he played only 25 minutes across France's two recent games.
Dembele has enjoyed a strong start to the season as the 21-year-old looks to put behind him a turbulent debut campaign in Spain.
"He is the same player as last season but what we want is for him to have an attacking mentality," Valverde said. "And we want him to be consistent."
Lopetegui would offer no clues as to the possibility of changes for Madrid against Bilbao.
Casemiro could be rested after he played for Brazil against El Salvador in the US on Tuesday but Gareth Bale is ready and available.
Bale played twice for Wales, and scored a stunner against Ireland to make it four goals in as many games for club and country.
"He has returned in phenomenal shape, no problems there," Lopetegui said.