Both men appeared in Iowa and New Hampshire on the first full day after the end of the party conventions.
Mr Obama conceded that the unemployment figures were "not good enough", while Mr Romney said the president's policies had failed.
The two men are neck-and-neck in the polls two months from Election Day.
Mr Obama's hope for a poll boost after the three-day Democratic convention, which finishing in North Carolina on Thursday night, faced a challenge from the latest set of weak economic data.
Friday's report by the Bureau of Labor Statistics showed 96,000 jobs were added in August, fewer than expected. The unemployment rate fell from 8.3% to 8.1%, but only because more people gave up looking for work.
The two men spent Friday campaigning in the swing states of Iowa and New Hampshire, with the president in New Hampshire in the morning before holding an evening rally in Iowa.
Mr Romney did the reverse, making his first appearance of the day in Sioux City, Iowa, before ending his Friday in Nashua, New Hampshire.
"That's not good enough," Mr Obama told a rally in Portsmouth, New Hampshire, talking about the jobs report. "We know it's not good enough.
"We need to create more jobs faster. We need to fill the hole left by this recession faster."
Mr Romney kept up his campaign's focus on lambasting the president's handling of the economy, pouncing on the jobs figures