England coach Steve McNamara said his team needed a substantial improvement for their World Cup semi-final against New Zealand next weekend.
His team beat France 34-6 in Wigan on Saturday but were far from impressive for long periods of the match.
"That was very, very scratchy, our worst performance of the tournament," said McNamara.
"It was a substandard performance. We will need to be a whole lot better next week and we will be."
France only scored two tries in their three group fixtures but took the lead against England when Vincent Duport crossed in the fifth minute.
McNamara's team scored four times in 19 minutes - two each for wingers Josh Charnley and Ryan Hall - as they built a 22-6 lead at the break.
Sean O'Loughlin and Brett Ferres also touched down after the break but England were guilty of numerous handling errors and squandered possession far too cheaply.
"In our previous three games we have shown how good we can be," added McNamara. "But tonight, if we needed a reminder or a wake-up call, that was it.
"We need every player to contribute, to be good, but in the second half the error count was one of the highest I have seen.
"As a coach I could sense that we were not on the mark, we could not find our rhythm."
And McNamara is confident his team will be substantially better when they take on the world champion Kiwis in the first of the Big Hit semi-final double-header in London.
"Our team play better when there is an element of fear in the back of their minds - the challenging game when they know what the consequences will be if they do not get it right," said the former Bradford Bulls coach.
"We will review everything that we have done, but there is no massive drama for me.
"We are in a semi-final at the national stadium. I believe there are 60,000 tickets sold already. We know we will need to be a whole lot better and we will be."
Captain Kevin Sinfield felt that his team lacked intensity but promised they would work hard to put it right before taking on a team that has scored 34 tries in four fixtures at the World Cup.
"For whatever reason we were not good enough and we are all thoroughly disappointed in the changing rooms," said the stand-off.
"Thankfully we got the win in the end, but it was not pretty and we have a big week in front of us. We need to be better in all areas."
France are coached by Englishman Richard Agar, who is also in charge of Super League side Wakefield.
His French side lost 48-0 to New Zealand during the group stage and Agar agreed that England will need to step it up if they are to reach the final.
"Against New Zealand they will have that bit of fear in bellies that they did not have against France," said Agar.
"I would still suggest that from what most of us have seen, I'd have Australia and New Zealand down as favourites but England have enough world-class talent.
"If they get it right on the day on home soil - there are a lot of things in their favour that can help tip the balance."