The Scotland captain approached the linesman, who then thrust his elbow into Robertson’s chin.
Robertson was shown a yellow card by referee Paul Tierney as he furiously protested.
Arsenal led 2-1 at half-time, but Liverpool rescued a 2-2 draw as Roberto Firmino’s 87th-minute header dented the leaders’ bid to win the title for the first time since 2004.
Hatzidakis now faces an investigation into his conduct after referees’ governing body PGMOL said they would review the incident.
“PGMOL is aware of an incident involving assistant referee Constantine Hatzidakis and Liverpool defender Andrew Robertson at half-time during the Liverpool v Arsenal fixture at Anfield,” the statement said.
“We will review the matter in full once the game has concluded.”
Liverpool manager Jurgen Klopp confirmed that the officials had not reached out to him or Robertson to offer an apology.
“I didn’t see it,” said Klopp of the incident. “I heard the pictures speak for themselves.”
Fulham striker Aleksandar Mitrovic was this week given an eight-match ban for pushing referee Chris Kavanagh in the Cottagers’ FA Cup defeat against Manchester United last month.
Former Manchester United midfielder Roy Keane, working at Anfield as a Sky Sports pundit, questioned Robertson for approaching the official, calling the defender “a big baby” for his reaction.
But fellow Sky pundit Gary Neville believes it will be Hatzidakis who finds himself in trouble this time.
“I’ve never seen an official raise an elbow to a player,” said Neville. “I think he’ll be in a lot of trouble after this game ends.”
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