Donald Trump took questions from the press after the summit concluded in Singapore. (AFP)

US President Donald Trump said the recent G7 spat-dominated meeting in Canada was "good", but in the same breath warned the host country would pay for the comments of its prime minister.

"I had a very good meeting with the G7," Trump said, rejecting suggestions the summit was a failure. But he also said that critical comments from Justin Trudeau would cost Canada "a lot of money".