Leon were pulled from the June 14-July 13 tournament over multi-club ownership rules, though the Court of Arbitration for Sport (CAS) has registered Leon's appeal against the decision.
"In a couple of weeks we will have the final and definitive decision, we will respect any decision," Infantino told reporters at the Mercedes-Benz Stadium in Atlanta on Monday.
"What we are looking at is that, if CAS confirms the decision of the Appeals Committee, FIFA's intention is to play a match, a playoff, between the team that lost the final of the CONCACAF Champions League, LAFC, and the next team in the ranking, which is America."
World football's governing body has said $1 billion prize money will be on offer at the expanded 32-team competition.