According to media reports, the guards were seized on February 6 in the Iranian province of Sistan-Baluchestan by militants who took them across the border to Pakistan.
"If Pakistan doesn't take the needed steps to fight against the terrorist groups, we will send our forces to Pakistan. We will not wait for this country," Iranian Interior Minister Abd AlReda Rahmani-Fadli was quoted as telling Mehr news agency.
A terrorist group calling itself Jaish al-Adl (Army of Justice) had claimed responsibility for the kidnapping.
The Iranian armed forces' deputy chief of staff was quoted as telling Fars news agency that Iran would "show tough confrontation in this case".
"We will have no soft stand in this case and our neighboring country ... should account for its lack of action," Major General Hussein Hassani Saadi told reporters in Tehran on Monday.
Saadi said the guards were still alive, and underlined that "political and military measures are underway to set them free", without elaborating.
Meanwhile, Iranian and international activists have begun a campaign known as #FreeIranianSoldiers on social media websites, calling for the release of five Iranian border guards.
In October, 14 Iranian border guards were killed and three others captured in the same area in an attack that was carried out by Jaish al-Adl.
The al-Qaeda-linked militant group has claimed a number of attacks and kidnappings since 2003, including a 2010 suicide bombing that killed dozens of people at a mosque.
BA/BA