"We have written to the external affairs ministry about it. If the Canadians don't respond, we will retaliate," Home Secretary G K Pillai told.
Asked if Canadians would be denied visas to India as a retaliatory measure, Pillai said: "Let's see. It all depends on how they respond."
Pillai said India will wait for a few days before deciding the course of action. "We will wait to hear from them. Let's give them a few days' time," said Pillai.
He, however, refused to spell out possible retaliatory steps India may take against Canada over what is widely seen here as the denial of visa on extraneous grounds.
Pillai added that the external affairs ministry had summoned the Canadian high commissioner last week and sought an explanation.
One way to retaliate would be to deny visas to Canadian officials who go to Afghanistan via India, said highly-placed sources.
The home ministry wants the Canadian high commission to apologise, take back the comments and take action against the officers responsible for rejecting visas, the sources said.