He acknowledged there was "reluctance" in Europe about his demands for the backstop - the plan to prevent a hard border with Ireland in all circumstances - to be scrapped.
"The House of Commons agreed the date it would rise for summer recess, as well as its return on 3 September, and this was passed by a majority of close to 200 MPs", she said.
"Business does have to prepare but I think, above all else, what this shows is that we must be trying to get a deal".
A document leaked over the weekend detailing preparations under Operation Yellowhammer argued the most probable scenario was severe, protracted delays to medicine supplies and shortages of some fresh foods, along with price rises, if there were a no-deal Brexit on 31 October.
"Settlement scheme for European Union residents in Britain remains as previously set out".
"Brexit will clearly be a key topic at Merkel and Macron meetings".
"He has been clear that there can not be any actual negotiations unless the backstop goes and that's the message he has delivered to leaders in his phone conversations and he will do that face-to-face", the Downing Street spokeswoman said.
Carolyn Fairbairn, director general of the Confederation of British Industry (CBI), said on Monday the alarming scenarios included in a government report leaked on Sunday felt like "plausible outcomes".
Securing an agreement required "compromise on both sides", she added in an interview on BBC Radio 4's Today programme.
Anti-Brexit campaigner Gina Miller has said the Government "unequivocally" accepts that it can not close down Parliament to allow a no-deal Brexit.
More than 100 MPs have signed a letter demanding Mr Johnson recalls Parliament, and Mr McDonnell said he too backed the move.
But Michael Gove, the government minister co-ordinating United Kingdom no-deal planning, tweeted that Yellowhammer was a "worst-case scenario", and did not reflect the "very significant" acceleration of no-deal planning in recent weeks.