Since the atrocity took place, thousands of people have used messages like "PrayForLondon" on social media to show solidarity with the capital and Khalid Masood's victims.
But Sam Cooke, 31, said the messages were "crap" and questioned why there had not been similar outpourings of support for people killed in other countries.
In an Instagram post, the photographer raged: "I can't stand all this 'prayforlondon' 'prayforparis' prayforbelgium' crap!!!!!!
"What about the 30 civilians that were killed by an American air strike in Syria yesterday? Or do those lives not matter?
"Yes it's a tragedy and my heart goes out to the families involved but people are killed all day everyday all over the world, stop choosing who you care about dependant on who the media tells you to care about.
"A life is a life! PRAY FOR THE WORLD."
More than 500 'liked' the post but other Instagram users left scathing comments.
Clare Sumner wrote: "Can't believe your disgusting disrespectful comments. I hope you never lose a loved one."
Others branded her post "shameful", with one writing: "It's happening in our own country the place we live in and raise our children in the city we live.
"Of course people are goin to feel more emotionally connected to this than Syria I do I get what your saying but the # thing is not crap, bad choice of word.
"It's how people show there thinking of the situation what else can we do???"
However, others rushed to her defence, with one praising her for speaking "the truth".
One wrote: "What she said is that we should morn EVERYONE!! She never said not to mourn for London!"
We are one world, one race and only by doing good will we drown out those who mean to do others harm. #UnitedTogether— Chris Smalling (@ChrisSmalling) March 23, 2017
In contrast, Man United star Chris Smalling, who was withdrawn from the England squad on Friday, used the hashtag "UnitedTogether" to call for solidarity.
Tweeting on Thursday, he wrote: "Stay united in times like this and support each other whatever the religion or beliefs.
"We are one world, one race and only by doing good will we drown out those who mean to do others harm. #UnitedTogether"