Pardew was sent to the St James' Park stands shortly after striker Demba Ba gave the hosts a 54th-minute lead and then he frantically tried to get a faulty walkie-talkie working so he could send messages back to the bench.
In the end, club officials had to do relay runs down the steps of the stand to pass on instructions to his assistants.
A fine or touchline ban could now follow from the Football Association but Pardew was full of regret.
"It was ridiculous really, I have to apologise publicly, I've been to see [the officials] already," he told ESPN television.
"I've been telling my players this week to behave and have the Olympic spirit. I can only apologise. It was stupid. I don't know what I was thinking."
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