The US government has warned its citizens the threat of terrorism in Northern Ireland is severe and they should exercise vigilance.
The US Consulate General in Belfast also warned Americans that they should avoid loyalist protests, as they often turn violent.
"Throughout 2013, a number of protests in and around Belfast have been characterised by violence aimed primarily at the police," the Consulate General said in a statement.
"Even demonstrations intended to be peaceful can turn confrontational and possibly escalate in to violence. We recommend that US citizens avoid the areas where such demonstrations are occurring."
In the wake of this week's attempted car bombing in Belfast city centre, the statement also warned innocent bystanders can get caught up in terrorist attacks.
"Most attempted attacks are aimed at law enforcement or military personnel or facilities, but there is risk to anyone in the vicinity of such an attack. We urge US citizens to maintain situational awareness and avoid any suspicious activity, vehicles, or packages," the statement added.
Earlier, the Deputy First Minister warned that UVF and elements of the Orange Order are behind this weekend's planned flags protest in Belfast.
Martin McGuinness also urged the UVF-linked Progressive Unionist Party to recognise the potential damage it could cause.
He told MLAs at question time that it had been a "very damaging" year here, and again pointed the finger at the UVF and "elements" of the Orange Order for fomenting trouble on the streets.
He also attacked dissident republicans, who he said tried to create mayhem in Belfast, despite having no support in the community.
To both he said: "It isn't going to work."
Asked by the SDLP's Alban Maginness if he agreed the flag protesters have made their point and should desist from Saturday's first anniversary protest, the Deputy First Minister said the media had become "exercised" over who is organising the parade.
"I don't have any doubt as to who's organising this parade. This parade is being organised by the UVF," he said.
"And it is being supported by elements within the Orange Order."
The Sinn Fein politician was also asked by Ulster Unionist MLA Samuel Gardiner whether or not the Dublin government would be involved in the ongoing Haass discussions on parades, flags and dealing with the legacy of the Troubles.
He replied it had been a "very damaging year, in which we clearly saw elements such as the Ulster Volunteer Force and elements of the Orange Order in north Belfast and other parts of Belfast fomenting conflict on the streets".
The Deputy First Minister said a failure by local politicians to find acceptable solutions would leave openings for dissident republicans and loyalist paramilitaries to attack the power-sharing institutions.
On the role of Dublin, Mr McGuinness said very few would expect Dr Haass to move forward without speaking to the London and Dublin governments.
US Consulate General advice
"The UK government and Police Service of Northern Ireland continue to assess the threat of terrorism in Northern Ireland to be severe.
"Most attempted attacks are aimed at law enforcement or military personnel or facilities, but there is risk to anyone in the vicinity of such an attack. We urge US citizens to maintain situational awareness and avoid any suspicious activity, vehicles, or packages.
"Throughout 2013, a number of protests in and around Belfast have been characterised by violence aimed primarily at the police.
"Even demonstrations intended to be peaceful can turn confrontational and possibly escalate into violence.
"We recommend that US citizens avoid the areas where such demonstrations are occurring if possible, and, as always, exercise caution in the vicinity of any parades or protests."