It did not specify whether the brigades would be deployed inside Gaza.
Israel said Sunday that Hamas is holding hostages in Rafah in southern Gaza, where Prime Minister Benjamin Netanyahu has vowed to launch a ground invasion despite international outcry.
"Hamas is still holding our hostages in Gaza... We also have hostages in Rafah, and we will do everything we can to bring them back home," Israeli military spokesman Rear Admiral Daniel Hagari said at a briefing.
In a separate statement, the army said it was calling "approximately two reserve brigades for operational activities on the Gazan front".
It did not specify whether the brigades would be deployed inside Gaza.
The move comes just days after the army pulled out all troops from southern Gaza's main city of Khan Yunis, leaving just one brigade to carry out operations across the Palestinian territory.
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