Britain said last week it was reviewing all arms export licenses to Israel after fierce fighting which has resulted in heavy civilian casualties in the Palestinian enclave of Gaza.
That review concluded on Tuesday that 12 licenses would be temporarily suspended pending further investigation if the current truce breaks down and heavy fighting resumes.
"The UK government has not been able to clarify if the export license criteria are being met," Business Secretary Vince Cable said in a statement.
"In light of that uncertainty, we have taken the decision to suspend these existing export licenses in the event of a resumption of significant hostilities."
Israel says its operation in Gaza is self-defense, aimed at stopping rockets being fired from the enclave by Islamist militants.
According to a report by a British parliamentary committee last month, outstanding government-approved contracts for export of dual use or military goods to Israel are worth more than 7.8 billion pounds ($13 billion). These include contracts to supply body armor, drone components and missile parts.
Cable's department said the vast majority of export licenses were not for items that could be used by Israeli forces in its operations in Gaza, but it was unable to immediately confirm the value of the licenses that could be suspended.
Britain said that the suspensions would not include components for Israel's "Iron Dome" system which protects the country from rockets fired by Hamas.
Last week Sayeeda Warsi, a senior Foreign Office minister, resigned, accusing Prime Minister David Cameron's government of taking a "morally indefensible" approach on Gaza.