He said this in an interview with Aljazeera TV on Wednesday.
"We will not sit (with arms folded) to wait for what others will do to us. Some military commanders in Iran are convinced that preventive operations which the Americans talk about are not their monopoly," Shamkhani said when asked about the possibility of a US or Israeli strike against Iran's nuclear facilities.
"America is not the only one present in the region. We are also present, from Khost to Kandahar in Afghanistan; we are present in the Gulf and we can be present in Iraq," said Shamkhani.
Earlier, the Iranian press reported a commander of the elite Revolutionary Guards as saying Iran will strike the Israeli reactor at Dimona if Israel attacks the Islamic republic's nuclear facilities.
"If Israel fires one missile at Bushehr atomic power plant, it should permanently forget about Dimona nuclear centre, where it produces and keeps its nuclear weapons, and Israel would be responsible for the terrifying consequence of this move," General Muhammad Baqir Zolqadr warned.
The minister's and the general's comments mark an escalation in an exchange of threats between Israel and Iran in recent weeks, leading to speculation that there may be a repeat of Israel's strike against Iraqi nuclear facilities at Osirak in 1981.
Iran's attempt to generate nuclear power at its plant being built at Bushehr is seen by arch-enemies Israel and the United States as a cover for nuclear weapons development.
But Iran insists that its nuclear intentions are peaceful, while pointing at its enemy's alleged nuclear arsenal, which Israel neither confirms nor denies possessing.
Israel within range
Dimona, in the Negev desert, is allegedly where Israel produces weapons-grade plutonium for its estimated 200 nuclear warheads.
Revolutionary Guard chief Yad Allah Javani warned on Sunday that "the entire Zionist territory including its nuclear establishments and atomic munitions are now within the range of Iran's advanced missiles".
Iran says its nuclear programme
is used to generate electricity
The statement came a few days after the Islamic republic conducted what it called a successful test of an upgraded version of its conventional medium-range Shahab-3 missile.
The missile is considered the mainstay of Iran's military technology and portrayed as defensive and dissuasive, but also specifically as a weapon against Israel.
The Revolutionary Guards, or Sepah-e Pasdaran, to whom the Shahab-3 has been entrusted, exist in parallel to the regular armed forces. They are well equipped and have a navy and air force as well as ground troops.
"Israel is not capable of attacking Iran and its threats are only propaganda"
Muhammad Baqer Zolqadr,
Revolutionary Guards chief
Zolqadr, however, considered that "given the internal crises in the Zionist regime and its military, security and geographical vulnerability, Israel is not capable of attacking Iran and its threats are only propaganda".
The threats, said General Zolqadr, were intended to deprive Iran of its "indisputable right" to nuclear technology for peaceful ends.
Israel in July tested an improved version of its Arrow II anti-missile system, aimed squarely at fending off any attack by Iran.