Acting Labour leader Harriet Harman said David Cameron "should remember he is talking about people, not insects" following his "swarms" comment.
She told the BBC the Prime Minister appeared to want to whip people up against the migrants.
Ms Harman also dismissed calls for the British Army to be sent in to sort out the problem.
I think it's a very worrying turn that he appears to be wanting to be divisive and set people against, whip people up, against the migrants in Calais when what he should have been doing, and should have been doing months ago and was warned to be doing, is to get the situation sorted out with the French.
A joint police operation has been launched to target people-smugglers who profit from the desperate migrants trying to reach the UK.
Calais' Mayor has accused Cameron of treating the region with "contempt" - and called on authorities to open the border unless help is given
More fencing and extra sniffer dogs have been sent from the UK to Calais in a bid to curb migrant incursions into Britain.