The Islamist group Hamas has urged Palestinians to abandon peace efforts and launch a new uprising against Israel in response to US President Donald Trump's recognition of Jerusalem as its capital.
The Israeli military said it was reinforcing troops in the occupied West Bank, deploying several new army battalions and putting other forces on standby, describing the measures as part of its "readiness for possible developments".
Protests on Thursday have so far been scattered and largely non-violent.
But dozens of Palestinians gathered at two points on the Gaza border fence with Israel and threw rocks at soldiers on the other side. Inside Gaza, thousands of Palestinians rallied, some chanting: "Death to America! Death to the fool Trump!" and burning tyres.
Trump reversed decades of US policy on Wednesday by recognising Jerusalem as the capital of Israel, imperilling Middle East peace efforts and upsetting the Arab world and Western allies alike.
The status of Jerusalem - home to sites holy to the Muslim, Jewish and Christian religions - is one of the biggest obstacles to reaching a peace agreement between Israel and the Palestinians.
"We should call for and we should work on launching an intifada (Palestinian uprising) in the face of the Zionist enemy," Hamas leader Ismail Haniyeh said in a speech in Gaza.
Haniyeh, elected the group's overall leader in May, urged Palestinians, Muslims and Arabs to hold rallies against the US decision on Friday, calling it a "day of rage".
Naser Al-Qidwa, an aide to Palestinian President Mahmoud Abbas and senior official in his Fatah party, urged Palestinians to stage protests but said they should be peaceful.
Israel considers Jerusalem its eternal and indivisible capital. Palestinians want the capital of an independent state of theirs to be in the city's eastern sector, which Israel captured in the 1967 Middle East war and annexed in a move never recognised internationally.
