The former Celtic man was also hit with a one-year supervision order after pleading guilty to the attack on PC Edward Gilmartin and Sergeant Tony Fitzpatrick in Airdrie last August.
The 26-year-old had a not-guilty plea to acting in a threating and abusive manner and kicking special constable Martine McNee on the body accepted by prosecutors at Airdrie Sheriff Court.
Scottish Premiership club St Mirren have vowed to do all they can to ensure McGowan learns from his mistakes.
A statement on their official website said: "Today's sentencing brings this deeply regrettable matter to a close.
"We have been very clear that we do not condone Paul's actions in any way. Everyone involved with St Mirren Football Club is fully aware that we expect them to act in accordance with our commitment to respect and tolerance in our community.
"Paul knows what he did was wrong and completely unacceptable. As a club, our long-term objective is to help him learn from his behaviour and move on with his life and career and, as such, we have no further comment to make."
McGowan initially joined the Paisley club on loan from Scottish champions in 2010 and completed a permanent move the following year.
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