Sinn Fein activists have been repeatedly warned not to send offensive or harassing material to people online in guidelines issued by party headquarters.
The party has also warned members and supporters not to discuss internal party matters online and not to repost material from people "who are politically opposed to us".
A "casual, naive or irresponsible approach" to social media like Facebook and Twitter can "cause problems for the party", the guidelines state.
The guidelines have been repeatedly issued to party activists across the country in recent weeks amid concerns about their use of social media.
A senior Sinn Fein source said: "You need to constantly do it because people keep saying silly things."
The document, entitled 'Social Media Guidelines for Activists', states that it should "always be borne in mind that these are public forums" and posts "are as accessible to the public and journalists as any statement issued by the press office".
Activists are reminded to "be responsible for your content and exercise good judgement and common sense about what you post" and are told not to "send offensive or harassing material to others".
The guidelines add: "Do not discuss any internal party matters online.
"Discussions or debates with other members, about internal party issues, should not be conducted online.
"Posts should be clean of foul language and activists should be respectful towards people no matter how obnoxious they may appear or sound."
The guidance states that "trolls" should be avoided.
Concerning "trolls", the Sinn Fein advice also states: "Check out the profile of the person you are engaging with - it should give you clues as to whether they are a troll or not.
"A troll will be there to goad you - to try and get you to drop your guard and say something inappropriate out of anger or frustration. Don't fall for it!"
Party activists are also urged to use statistics and figures from Sinn Fein publications and policy positions to support their arguments and beware of posting other people's or organisations' content.