The former deputy prime minister announced on Saturday he would not stand for his NSW seat of New England at the next election, citing an irreparably broken relationship with the Nationals' leadership, but would see out the rest of the parliamentary term.
The move has prompted speculation Mr Joyce could defect to Pauline Hanson's One Nation.
Mr Littleproud said Mr Joyce still had a critical role to play within the party and urged him to stay inside the coalition.
"We want him to stay in the National Party. I think he has a contribution to make between now and when he retires," Mr Littleproud told Nine's Today program  on Sunday.
"So obviously we all will be talking to Barnaby. We want to make sure that his contribution is a valued one within our party room, as everybody is."
The Nationals leader said Mr Joyce had not tendered his resignation from the party.
Mr Joyce said his relationship with the junior coalition party had broken down, following the last election when he was demoted to the backbench.
"I am free to now consider all options as to what I do next," he said in a letter to branch members.
"The atmospherics in the party room, where I am seated in the far corner of the coalition in the chamber, means I am seen and now turning into a discordant note.
"That is not who I want to be."
He said the debate surrounding net-zero emissions, which he has called for the coalition to dump, has been a sticking point.
The Nationals leader said he was looking to speak to Mr Joyce for contributions on policy.
"I'll be reaching out and having a conversation and making sure he understands that he, along with the rest of us, will play a very important role in shaping the coalition and helping the coalition rebuild," Mr Littleproud said.
"We've got to make sure that we're not just a party of protests, we're a party that can govern and say to the Australian people, there's an alternative way to address climate change."
Liberal frontbencher Jonathon Duniam said a move to another political party during the current term would be disingenuous to voters.
"I don't think if he had an intention to defect to another party that he should sit as a Nat in parliament, or at least in the same party room as the National Party. I think that would be unworkable," he told Sky News.
"Moving to One Nation, while he might be able to continue his time in parliament, would be one thing. I think it's important to respect those who run you to the dance, and in this case, it was the Nats."
Education Minister Jason Clare said he wished Mr Joyce well if the statement was an indication of his impending retirement from politics.
"Not just the National Party, but the Liberal Party too, are in a world of pain here at the moment," he told Sky News.
"They need to work out whether they want to be Howard or Hanson, they'll eventually work this out, they always do that."
27°C