OTTAWA — A Conservative senator said Thursday he won't apologize for comments he made to a crowd of protesters, asking them to "roll over every Liberal left in the country."

"The words I used may not have been as artful as I would have liked and certain individuals are happy to misinterpret them to suit their own self interest," Saskatchewan Sen. David Tkachuk said in a statement.

Tkachuk said he was asked by the Greater Ottawa Truckers Association to speak to a few hundred "United We Roll" protesters gathered on Parliament Hill Tuesday.

It was a figure of speech. And just as the Minnesota defensive line, known as the "purple people eaters," didn't actually eat people, and the Denver Broncos "orange crush" didn't actually crush people, and the Pittsburgh Steelers' "Steel curtain" offensive line wasn't actually steel, neither did I mean Liberals should be literally rolled over. - Statement from Sen. David Tkachuk

A 200-vehicle convoy, some who travelled from Red Deer, Alta., held a two-day protest in the nation's capital to voice their concerns over a range of issues, including, primarily, job security in Canada's oil and gas industry.

"I know you've rolled all the way here, and I'm going to ask you one more thing: I want you to roll over every Liberal left in the country," the Saskatchewan senator told the crowd. "Because when they're gone. These bills are gone."

The bills he was referring to are two pieces of government legislation known as Bill C-69 and Bill C-48 which the Conservatives believe will harm Canada's energy industry. Bill C-69 seeks to overhaul the review process for major projects. And Bill C-48 proposes an oil tanker ban in northern British Columbia.

Tkachuk told HuffPost Canada on Wednesday that he felt obligated to show his support for oil and gas workers, many of whom travelled far distances to be in Ottawa for the "United We Roll" rally.

The senator's comments drew the ire of Canada's top civil servant Thursday.

Michael Wernick, the clerk of the Privy Council, opened his remarks at the House of Commons' justice committee with a reference to Tkachuk's choice of words at the rally.

"I think it's totally unacceptable that a member of the Parliament of Canada would incite people to drive trucks over people after what happened in Toronto last summer," Wernick said.

Ten people were killed last year after a driver drove a van onto the sidewalk of a busy street. The victims ranged in ages between 22 and 94.

"It's totally unacceptable, and I hope that you, as parliamentarians, are going to condemn that," he said, without mentioning Tkachuk's name

Watch: Michael Wernick explains why he's worried about the state of Canadian politics