Ireland Rugby Football Union had to turn off comments on a social media post which congratulated debutant Edwin Edogbo, following replies which contained racial abuse.
Munster forward Edogbo came off the bench and played the final 10 minutes of Ireland's 20-13 victory over Italy in the Six Nations.
The IRFU confirmed in a statement the comments made on the social media post on Saturday are now subject to investigation.
"We're aware of some targeted abuse online in recent days and continue to work with Signify and the relevant authorities to report it," the full IRFU statement read.
"We will also continue to fully support all affected by the cowardly actions of a minority and investigations are under way alongside our partners Signify.
"It is clear that racist abuse has no place in Irish society and the IRFU has a zero-tolerance policy towards racism of any form."
The 23-year-old lock has made 24 appearances for Munster and has registered 30 points.
After Ireland's nervy victory on Saturday, Ireland head coach Andy Farrell praised the debutant's contribution in his post-match press conference.
"Well, we need to celebrate Edwin's first cap, that is for sure as it is one amazing story," Farrell said.
"I am so pleased we were able to get a win and show some fight to get a win for him because his story is a phenomenal one so we will celebrate that with him."