Xavier Bettel said Mr Johnson had failed to put forward any serious plans to allow a deal by 31 October.
But Mr Johnson, who cancelled his press conference because of the noise from protesters, said “there’s been a lot of work” and “papers have been shared”.
He urged the EU to make “movement” in its opposition to scrap the backstop.
Mr Johnson said his joint press conference was cancelled over fears the two leaders would have been “drowned out” by pro-EU protesters.
“I don’t think it would have been fair to the prime minister of Luxembourg,” he said.
“I think there was clearly going to be a lot of noise and I think our points might have been drowned out.”
Political editor Laura Kuenssberg said that Number 10 had asked for the press conference to be held inside, according to sources.