The Coalition of Irish Immigration Centers (CIIC) says it has done so due to changes in immigration enforcement policy under President Donald Trump.
It says the focus has been on people from seven countries named by the president and those with deportation orders or criminal histories.
"This applies to a small portion of the Irish community," it adds.
"Given the change in immigration enforcement policy and implementation, the immigrant community is strongly advised to be vigilant in obeying all local and state laws, especially when driving."
It also advises "those who feel they are at risk of deportation" to speak to a lawyer and be screened for possible benefits or relief.
"Have an emergency and family plan in place in case of arrest, especially involving children."
The organisation advises people to "be wary of rumours about ICE [Immigration and Customs Enforcement] activity, ICE raids or immigration policy changes".
It said Immigration and Customs Enforcement had recently carried out focused enforcement actions and community arrests of about 680 non-citizens, most with criminal histories or prior orders of deportation.
"This operation was not unlike previous enforcement actions in the past," it said.
"However, there have been some reports of secondary arrests of individuals who were not the original focus of the enforcement efforts, resulting from the fact that ICE now has broader authority to arrest anyone who is undocumented."
The Trump administration has issued tough guidelines to widen the net for deporting illegal immigrants from the US, and speed up their removal.
Undocumented immigrants arrested for traffic violations or shop-lifting will be targeted along with those convicted of more serious crimes.
The memos do not alter US immigration laws, but take a much tougher approach towards enforcing existing measures.
There are an estimated 11 million illegal immigrants in the US, about 50,000 of whom are believed to be Irish.
An organisation that represents immigrant groups has issued new advice to Irish people in the US.