Medics said one man was killed overnight in an Israeli airstrike in the Bureij camp in the central area of the enclave, while another strike killed one person and wounded others in Gaza City.
The two deaths were the latest violence to overshadow the US-brokered ceasefire deal signed in October after two years of full-blown war between Israel and Hamas.
Progress on moving forward with parts the deal, which include the disarmament of Hamas and Israeli army pullouts, has stalled.
The Israeli military didn't immediately comment on either incident.
The ceasefire that began in October left Israeli troops in control of a depopulated zone that makes up well over half of Gaza, with Hamas controlling the narrow coastal strip that remains.
More than 750 Palestinians have been killed since the ceasefire deal took effect, according to local medics, while Israel says militants have killed four of its soldiers. Israel and Hamas have traded blame for ceasefire violations.
Israel says it aims to thwart attacks by Hamas and other militant factions.
Also on Monday, residents and sources close to Hamas said members of an Israeli-backed militia operating in an area under Israeli control clashed with Palestinian fighters after crossing into a Hamas-run area east of Khan Younis.
As the militiamen tried to retreat, a Hamas fighter fired an anti-tank grenade towards their vehicle, some residents and a Hamas source said. An explosion was heard, but there was no word about casualties.
A video, verified by Reuters, showed gunmen apparently from the militia dressed in black uniforms and clutching AK assault rifles arriving at a Hamas-run area in eastern Khan Younis before shooting is heard.
There was no comment from either Hamas, which brands such groups as "Israeli collaborators", or the militia, about the incident.
The emergence of the groups, though they remain small and localised, has added to pressures on Islamist Hamas and could complicate efforts to stabilise and unify a divided and shattered Gaza.
The groups remain unpopular as they operate under Israeli control.
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