She repeatedly targeted companies, including SodaStream and Ahava, and encouraged others to “hold Israel accountable for its violation of international law”.
Ms Tolhurst also posted critical messages relating to Israeli military action in the Gaza Strip.
She backed a petition calling on Foreign Secretary Philip Hammond and David Cameron to send an RAF hospital ship to Gaza to assist with humanitarian efforts.
In November 2012, Ms Tolhurst said she was "disappointed" that Britain had abstained during the United Nations vote on Palestinian statehood. Only last week, in the wake of the Parliamentary vote on Palestine, Mr Cameron reasserted the government's position, saying recognition was an issue to include in peace negotiations.
During Israel's Pillar of Defence operation to stop Hamas rocket attacks she posted tweets using hashtags including #Palestineunderattack and #VivaPalestina.
The Conservative Party has not yet responded to a request for a comment on Ms Tolhurst’s stance.
In a statement issued to the JC, Ms Tolhurst said: "I obviously condemn violence on both sides and agree with the Prime Minister that it is always wrong for anyone to target civilians.
"I am personally committed to the two-state solution; and think that the priority for our country is to work with our international partners in the region to ensure that a lasting peace is firmly established in Israel and Palestine."
Mr Cameron and Mr Hammond were criticised by political opponents for their reluctance to criticise Israel in harsh terms during the conflict.
The Prime Minister has repeatedly said he is against boycotts of the country, telling the Knesset during a visit in March: “To those who… want to boycott Israel I have a clear message. Britain opposes boycotts.”
Mr Cameron also told Israeli politicians in Jerusalem: "Let me say to you very clearly: with me, you have a British Prime Minister whose belief in Israel is unbreakable and whose commitment to Israel’s security will always be rock solid.
"Delegitimising the state of Israel is wrong. It’s abhorrent. And together we will defeat it."
The by-election was called after incumbent Tory MP Mark Reckless defected to Ukip. Latest polling suggests he is well-poised to win the election on November 20.
Ms Tolhurst said she was “honoured” to be selected as the Conservative candidate. She won the open primary with 50.44 per cent of the vote.
