الشهر الحرام بالشهر الحرام والحرمات قصاص فمن اعتدى عليكم فاعتدوا عليه بمثل (2:194) بالانجليزي

(2:194) A prohibited month is to be respected, if the same is respected (by the enemy), *206 and likewise there is the law of just retribution for the violation of all prohibited things. Therefore, if anyone transgresses a prohibition by attacking you, you may do likewise, but always fear AIIah and bear in mind that Allah is with those who desist from breaking Allah's bounds.

Tafseer Abu-al-A'la Maududi

Page 30 English Traditional

*206). From the time of Abraham three months - Dhu al-Qa'dah, Dhu al-Hijjah and Muharram - were consecrated for Hajj, and the month of Rajab was consecrated for 'Umrah. For the duration of these four months warfare, killing and pillage were prohibited so that people could perform Pilgrimage and return home safely. For this reason these months were cajied the 'sacred months'.
The purpose of the verse is to stress that if the unbelievers respect the sanctity of the sacred months, the Muslims should do the same. If, however, they violate this sanctity and subject the Muslims to aggression, then the Muslims are also entitled to retribution even during the 'sacred months'.
The permission mentioned here was called forth by the introduction of nasi', a practice which had been introduced by the Arabs in order to have an advantage over others in their battles and raids. The manner in which the Arabs used nasi' was such that whenever they wished either to start a conflict in order to satisfy their vendetta or to loot and plunder they carried out their raid in one of the sacred months and then later on tried to compensate for this violation by treating one of the non-sacred months as a sacred month. The Muslims were, therefore, concerned as to what they should do in case the unbelievers resorted to this artifice and surprised them by an attack in one of the recognized sacred months. The verse refers to this problem.