The U.S. July nonfarm payrolls data, due to be released on Friday, is seen as a barometer of economic health and could influence the Federal Reserve's monetary policy decisions.

The benchmark TSX's decline came after gains in the previous six sessions.

"We're seeing pretty broad-based selling today. It looks like investors are getting a little nervous ahead of tomorrow's U.S. jobs report," said Youssef Zohny, portfolio manager at StennerZohny Investment Partners of Richardson GMP Ltd, which manages about C$28.3 billion in assets.

"Investors are looking for something close to expectations, but anything over or under that would likely lead to some concerns on the market," he added.

The Toronto Stock Exchange's S&P/TSX composite index <.GSPTSE> closed down 97.08 points, or 0.67 percent, at 14,405.91. Seven of the 10 main sectors on the index were in the red.

The energy sector, which accounts for 19 percent of the weight of the index, rose 1.6 percent, shrugging off a decline in U.S. crude oil prices amid a persistent global supply glut and little sign of a reduction in production. [O/R]

Suncor Energy Inc (>> Suncor Energy Inc.) added 0.5 percent to C$37.51. Canadian Natural Resources (>> Canadian Natural Resources Limited) advanced 1.5 percent to C$32.81 after a fall in production expenses that helped the country's largest independent petroleum producer report better-than-expected adjusted earnings.

Several earnings reports also influenced stock moves.

Shares in SNC-Lavalin Group Inc (>> SNC-Lavalin Group Inc) fell 8.4 percent to C$40.05 after the engineering and construction company said costly problems with two projects hurt its earnings.

Barrick Gold Corp (>> Barrick Gold Corp.) shares gained 4 percent to C$8.99 after the major gold miner said it is making big strides toward an ambitious debt reduction target, announcing a financing deal for its Dominican mine and the planned sale of a suite of U.S. assets.

Insurer Sun Life Financial Inc (>> Sun Life Financial Inc) jumped 5.4 percent to C$45.17 after reporting a quarterly profit that beat market estimates.

TMX Group Ltd (>> TMX Group Ltd), the operator of the Toronto Stock Exchange, fell 5.6 percent to C$47.14 after reporting a lower-than-expected quarterly profit, hurt by a drop in revenue at its issuer services and cash markets trading businesses.

In the financial sector, Bank of Nova Scotia (>> Bank of Nova Scotia) lost 1.9 percent to C$62.63. Valeant Pharmaceuticals International Inc's (>> Valeant Pharmaceuticals Intl Inc) 6 percent drop helped drag down the healthcare sector.

(Additional reporting by John Tilak; Editing by Matthew Lewis and James Dalgleish)

By Alastair Sharp