Leaders have clashed over proposals to grant the Ukrainian Orthodox Church independence from clergy in Moscow.
Justin Welby tweeted on Monday: "We are deeply saddened by the difficulties in relations between the Orthodox Patriarchates in Moscow and Constantinople, and their potential impact on Orthodox world.
"We are offering heartfelt prayers for a peaceful outcome."
Meanwhile, the Russian Orthodox Church has warned the Ukrainian Church's bid to formally break away from Russia's orbit may lead to violence.
The Istanbul-based Ecumenical Patriarchate announced last week that it was sending two bishops to Ukraine. This was viewed by many critics as a step toward declaring ecclesiastical independence for the main Ukrainian Orthodox church there.
Russian government spokesman Dmitry Peskov told reporters the Kremlin is following the situation closely and "for Moscow and indeed for the entire Orthodox world the single preferable scenario is the preservation of unity of this Orthodox world".
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