The Boys in Green came from behind to win 2-1, but the Sunderland midfielder objected to being an unused substitute for manager Giovanni Trapattoni, and let his feelings be known to his followers.
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He returned to Twitter on Saturday morning and wrote: "i apologise for my tweet last night, it was stupid, disrespectful and i let my frustration get the better of me which still aint an excuse."
McClean subsequently deleted his account on the social networking website, and Trapattoni is reported to know of the incident and will now decide whether to take any action against the midfielder.
The Sunderland man has made four appearances for the Irish national side since making his debut in 2012 against the Czech Republic, including playing in the 4-0 defeat to Spain in Euro 2012.
Ireland next face Oman in a friendly on Tuesday night at Fulham’s Craven Cottage.
You can watch Ireland's friendly with Oman on Tuesday exclusively live through Goal.com in the United Kingdom and Australia. Click here to subscribe.