World soccer's governing body has opened the bidding process for the 2018 and 2022 tournaments with 11 potential candidates having submitted their initial bids this week.
Four of those are from Europe comprising individual bids from England and Russia and joint bids from Spain/Portugal and Netherlands/Belgium.
"If FIFA does decide it is in Europe in 2018 it is not a problem, because then everyone will vote for a European bid but we have to know what FIFA's rules are first," Platini told Reuters after a news briefing.
"My job as the president of UEFA is to bring the World Cup back to Europe in 2018 and to convince FIFA because we have to come back to Europe every third time.
"If we get that then the four (European bidders) will fight for it," added Platini.
"If there is no European decision perhaps we can find another decision or tactic with the UEFA executive committee," said the head of the sport's European governing body.
Platini, a member of FIFA's executive committee, said if that was the case UEFA could ballot its members and submit one bid for 2018 so the European vote was not split among the 24-man FIFA executive which decides the issue in December next year.
As well as Europe's four bids to host the World Cup, FIFA has also received bids from Australia, Indonesia, Japan, South Korea, Qatar, United States and Mexico.
By 2018 it will be 12 years since Europe last hosted the World Cup, which was held in Germany in 2006.
The 2010 World Cup finals are being hosted by South Africa with Brazil hosting the 2014 tournament.
