Earlier this month, Mr Musk tweeted out a proposal that Ukraine accept Russia's annexation of Crimea and allow referendums in Ukrainian regions invaded by Moscow.
The Kremlin responded positively to the overture.
But Ukraine's outgoing ambassador to Germany, Andrij Melnyk, posted a tweet telling Mr Musk to go away, using a swear word.
Responding on Friday to a post referring to the ambassador's remark, Mr Musk said: "We're just following his recommendation."
Moscow recently declared four more Ukrainian regions to be part of Russia, following so-called referendums denounced as fraudulent by Kyiv and its Western allies. Russia does not fully control any of the four regions.
Mr Musk has also suggested the world should "formally" recognise Crimea - illegally annexed by Moscow in 2014 - as part of Russia.
This week, Mr Musk denied that he spoke to Russian President Vladimir Putin before releasing his Twitter poll.
"I have spoken to Putin only once and that was about 18 months ago. The subject matter was space," he tweeted.
That statement came after a think tank researcher claimed Mr Musk had personally told him about the alleged conversation.