Les Blues slumped to their third loss in as many games in the competition despite taking a lead into half time at Twickenham.
Saint-Andre told BBC Sport: "We had an opportunity at 10-9 for more points when England were not as confident, but we didn't take it. We have to learn from this and carry on.
"So many times we tried impossible offloads and lost the ball in the contact area and England didn't do amazing things, but they were accurate and we were not accurate enough."
France's next game is against Ireland on March 9.