The Leinster loosehead, who missed the Rugby Champions Cup ties against Castres and Wasps through suspension, admitted the incident was a painful lesson.
“I gave him a buzz just to apologise,” McGrath said yesterday. “There was no malice behind it. I felt he was near the ball and I felt that by rucking on him a few times he might move away from the ball.
“The referee obviously thought it was a bit too much. It was not something I should have done.”
He continued: “When I got the ban, it was just a case of trying to delete it from my mind and focus on whatever positives I could. That meant trying to help the squad as much as I could by going through videos with the front-row for the European games.”
Training has allowed him maintain fitness, but he needs game time before Ireland open their Six Nations title defence in Rome next month.
Yesterday’s injury update didn’t lend hope to Cian Healy being fit in time for that trip and, though Ireland also have Dave Kilcoyne and James Cronin to choose from in the loosehead department, McGrath started against South Africa and Australia in November.
Friday night’s meeting of the Ireland Wolfhounds and England Saxons in Cork should at least provide the Leinster prop — and one or two others — with a chance to see action.
“There is no substitution for playing rugby,” McGrath said. “Three weeks is probably a long time. Ideally, I wouldn’t have liked to have been out for three weeks.
“That’s what happened. With guys like Henry Thomas and Kieran Brookes, who, hopefully, I will be coming up against this weekend, they’re pretty strong operators. I will have to be on top form.”
Meanwhile, Wasps number eight Ashley Johnson has been cited for an alleged dangerous tackle on Leinster wing Dave Kearney in the 20-20 draw at the Ricoh Arena on Saturday.
Johnson tackled Kearney straight from the opening kick off in the European Champions Cup clash and was shown a yellow card by French referee Jerome Garces.