"This is exactly what extremists would want to see. But more importantly, he's missed the plot in terms of the violence that claims most American lives. It doesn't come from Muslim extremism, it comes from people within their own society."
Mr Shearer said he was optimistic Trump would be overtaken by a more sensible and humane Republican candidate.
"Ultimately he will be seen to be someone who doesn't really have a prescription of what to do other than build walls and to create bans. That is not going to create a United States that the world respects and admires."
The Labour MP said there was no public or political appetite for Trump's comments in New Zealand.
"I'd like to think that they would be shouted down by pretty much everyone in New Zealand as being not only an overreaction but likely to do real harm to our multicultural society."