The England forward, who appeared to go in high, sparked the anger of the home fans.
But he escaped a card from referee JP Doyle who, after consulting television match official David Grashoff, deemed the tackle worthy of only a penalty in the way of punishment.
"It wasn't the greatest hit of all time," said director of rugby McCall. "Alistair's on his feet but he's a bit groggy. I think a penalty on its own could be regarded as a bit lenient."
Wasps rugby director Dai Young saw it differently, stating: "I thought it was a good tackle.
"First and foremost, we hope the player's okay because nobody likes to see anybody going off, but the tackle looked okay to me."
Hargreaves scored Sarries only try while Charlie Hodgson kicked 21 points and Nils Mordt added a further penalty, leaving McCall satisfied with the way his side coped in the absence of a host of internationals.
He said: "The first half was a bit of a disappointment but I'm just proud of the players for getting the job done.
"It wasn't an easy day to play rugby and Wasps really put it to us. They were really physical and made life very hard. But, given the number of players missing, our younger players stepped up.
"I thought the difference between the two teams was our set-piece. The scrum and the lineout were excellent."
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