Prime Minister John Key says the two-year prison sentence imposed on all-female punk group Pussy Riot seems "disproportionate".
Nadezhda Tolokonnikova, 22, Maria Alekhina, 24, and Yekaterina Samutsevich, 30, were arrested in March after performing a "punk prayer" in Christ the Savior Cathedral in Moscow.
While dancing and high-kicking, they called on the Virgin Mary to save Russia from Vladimir Putin, who was elected to a third term as Russia's president two weeks later.
The three activists were sentenced to two years in prison for hooliganism on Friday, a decision that drew protests around the world as it highlighted the Russian president's intensifying crackdown on dissent.
"I've been following the case in the world sections of the newspapers I've been reading.
"I can't say I've had any official advice on it - but it does seem disproportionate to me, two years is quite a long sentence," said Mr Key.
He said he may raise the topic with Mr Putin while in Russia for the Asia Pacific Economic Cooperation forum in Vladivostok, but it was not top of his list.
"It's more likely that our ambassador will raise it with foreign services in Russia," he said.