A video shared on social media on Friday afternoon appears to show a woman throwing a drink at Leo Varadkar in Dublin.
The footage shows a woman approaching the Tánaiste, who was preparing to give an interview on camera.
The woman stands near the Tánaiste and the camera crew gathered in front of him. She then heads to Mr Varadkar and throws a drink in his face before running away.
Former TD Noel Rock called it "a poxy thing to do, regardless of your political view".
Writing on Twitter, former presidential candidate Gavin Duffy said the incident was “horribly uncouth”.
“This is an attack on our democracy not him,” he said.
“It’s reported it was coffee but it could have been anything including acid. We need to better protect our politicians.”
Mr Varadkar's spokesperson has been contacted for comment.
