The arrested were identified as Baljeet Singh (Mohali resident), Bikar Singh (Sangrur), Kulwinderjeet Singh (Ludhiana) and Trilochan Singh (Panchkula), a senior police official said.
Four pistols and 125 live cartridges were recovered from them.
The militants, who were arrested on Thursday by elite anti-terror wing Special Cell, were planning a terror strike in the capital, the official said.
This is the first arrest of militants in the capital this year. Last year, 19 militants were arrested and four were killed in Delhi.