Specifically, the regulators said Airbnb must show people total prices up-front that include all charges and fees, and it must clearly tell customers whether a property is being offered by a private host or a professional.
The company has until the end of August to present its proposals for responding to the criticism which will then be reviewed by the Commission and national consumer authorities.
The commission has been cracking down on what is sees as risks for European consumers using the services of United States internet giants like Facebook, Google, Amazon, Uber and others.
The European Commission has raised various other points with Airbnb on which it is not complying with EU law, including denying consumers the basic legal right to sue a host in case of personal harm or other damages.
Airbnb said it was looking into the issues brought to its attention by the European Commission.
It also said the terms did not give consumers adequate protection in the event of a booking cancellation by the property owner.
EU Justice and Consumer Affairs commissioner Vera Jourova told a press conference the action might result "in different sanctions" by the national consumer authorities.
"But popularity can not be an excuse for not complying with European Union consumer rules".
Jourová, who is from the Czech Republic, added that the commission had received some 6,000 complaints about such accommodation services past year but the EU's executive regarded that as "the tip of the iceberg".
"We take this issue seriously and are committed to being as transparent as possible for our community", the company said.
She added that the warning would not come "out of the blue" to Airbnb, which is is said to be aiming to have 1 billion annual guests worldwide by 2028.
There have always been concerns about Airbnb's policies, along with its wider impact on the hospitality industry and residential rents, with local authorities increasingly looking to curb its presence.
If Airbnb does not propose "detailed solutions" on fixing the problems by the end of next month, there will be a meeting between the company and the regulators in September.