Lawmakers have twice rejected the deal. Britain is scheduled to leave the European Union on April 12 if no deal is approved.
In the letter to Tusk released by Downing Street, May said she intended to bring the Brexit deal she has negotiated with the EU back to parliament.
Queen Elizabeth II and British Prime Minister Theresa May led condolences from the UK following the deadliest terror attack in New Zealand's history.
The summit next week is seen as the last chance for Prime Minister Theresa May to secure unanimous approval from the other 27 EU members for any Brexit delay.
Jagtar Singh Johal, from Dumbarton in Scotland, was arrested by Indian authorities in November 2017 on charges of fanning communal disturbance in Punjab.
Though the British PM had promised of a second vote on the deal by March 12, some Brexit supporters are suggesting to postpone the vote rather than taking the risk of another defeat.
PM May ascertained that if the deal fails, Brexit may not happen at all.
British lawmakers are due to vote for a second time Tuesday on the deal, which they overwhelmingly rejected in January.
After the Pulwama attack, the Indian Air Force carried out a counter-terror operation, hitting what it said was a JeM training camp in Balakot, deep inside Pakistan on February 26.
Wednesday's meeting comes one day after British Prime Minister Theresa May said Parliament would get the chance to vote to delay Britain's scheduled March 29 departure from the European Union.