The European Commission says social media giants Facebook and Twitter have only partially responded to its demands to bring their practices into line with EU consumer law.
The Commission asked the two companies a year ago to change their terms of service following complaints from people targeted by fraud or scams on social media websites.
The EU's executive arm said Thursday that the firms only partly addressed "issues about their liability and about how users are informed of possible content removal or contract termination."
It said changes proposed by Google+ appear to be in line with demands.
Europe's consumer affairs commissioner, Vera Jourova, said "it is unacceptable that this is still not complete and it is taking so much time." She called for those flouting consumer rules to face sanctions.