Petkovic warned his side would have to vastly improve on Wednesday's lacklustre showing against Costa Rica.
FIFA said Xhaka and Shaqiri would each be fined 10,000 Swiss francs (8,700 euros, $10,000) and Lichtsteiner 5,000 Swiss francs.
The celebrations during Switzerland's 2-1 victory over Serbia on Friday have triggered a disciplinary investigation by FIFA and outrage from nationalist politicians at home.
Brazil's tag as pre-tournament favourites looked justified in a dominant first-half capped by Philippe Coutinho's wonder strike to open the scoring.
Vladimir Petkovic-managed side's World Cup prospects are one of the hardest to predict, and also the most intriguing.