Washington(CNN) FIFA directed attention to the organization's ethics rules following President Donald Trump's tweet supporting the North American bid to host the 2026 World Cup.

Trump tweeted on Thursday about the bid, saying it "would be a shame" if nations lobbied against its efforts.

"The U.S. has put together a STRONG bid w/ Canada & Mexico for the 2026 World Cup," Trump wrote on Twitter. "It would be a shame if countries that we always support were to lobby against the U.S. bid. Why should we be supporting these countries when they don't support us (including at the United Nations)?"

A FIFA spokesperson said in a statement, "As a general rule, we cannot comment on specific statements in connection with the bidding process. We can only refer to the FIFA Regulations for the selection of the venue for the final competition of the 2026 FIFA World Cup, and in particular to the Bid Rules of Conduct incorporated therein."

Those rules outline restrictions on countries' activities that "may adversely affect the integrity of the Bidding Process and create an undue influence on the Bidding Process," Reuters has previously reported.

The US, Canada and Mexico bid group said in a statement, "From the beginning, we have received great support from the Canadian, Mexican and United States governments. We are grateful for that support and together our three countries are ready to welcome players and fans from around the world to an extraordinary FIFA World Cup in 2026."

The formal North American bid announcement took place last April at a press conference at One World Observatory in the World Trade Center in New York.