Blocking assembly for at least one leaf of an elevator door (100, 100'), particularly a car door, comprising: - a translation guide extending along a sliding direction; - at least one first leaf carriage, slidably mounted to the translation guide between a first position (Fig. 1) and a second position (Fig. 2); - at least one latch connected to the translation guide and movable/rotatable between a blocking configuration of said first carriage in an intermediate position between the first position and the second position in which said latch intercepts the first leaf carriage to block it with respect to said guide, and a release configuration of said first carriage, wherein the latter is free to slide to the second position; - return means, e.g. comprising elastic means and/or counterweight means, of the latch in the blocking configuration; - first coupling means (10, 12) connected to the first leaf carriage and to the latch so that: i) when the first carriage is in the first position, said means (10, 12) are mutually coupled to keep the latch in the release configuration, in contrast to the action of the return means; ii) when the carriage is in the intermediate position (Fig. 4), said means (10, 12) are uncoupled so that the latch is moved by the return means to the blocking configuration; and wherein a second leaf carriage mounted to the translation guide, and wherein the latch is movable between a blocking configuration of said carriage in an intermediate position of the latter, and a release configuration of said carriage in which it is free to slide along the translation guide to a second position thereof with a movement opposite that of the first leaf carriage; and wherein - the latch and the first leaf carriage comprise first complementary engagement elements (14, 16) which in the blocking configuration cooperate by shape and/or by force to carry out said blocking, and which in the release configuration do not interact with each other or lie mutually spaced in a transverse or orthogonal direction with respect to the sliding direction; characterised in that: - the latch 6 and the second leaf carriage 4' comprise second complementary engagement elements 38, 40, which, in the blocking configuration, cooperate by shape and/or by force to carry out the aforesaid blocking, and which, in the release configuration, do not interact with each other or lie mutually spaced, e.g., in a transverse T or orthogonal direction with respect to the sliding direction X. - a translation guide extending along a sliding direction; - at least one first leaf carriage, slidably mounted to the translation guide between a first position (Fig. 1) and a second position (Fig. 2); - at least one latch connected to the translation guide and movable/rotatable between a blocking configuration of said first carriage in an intermediate position between the first position and the second position in which said latch intercepts the first leaf carriage to block it with respect to said guide, and a release configuration of said first carriage, wherein the latter is free to slide to the second position; - return means, e.g. comprising elastic means and/or counterweight means, of the latch in the blocking configuration; - first coupling means (10, 12) connected to the first leaf carriage and to the latch so that: i) when the first carriage is in the first position, said means (10, 12) are mutually coupled to keep the latch in the release configuration, in contrast to the action of the return means; ii) when the carriage is in the intermediate position (Fig. 4), said means (10, 12) are uncoupled so that the latch is moved by the return means to the blocking configuration; and wherein a second leaf carriage mounted to the translation guide, and wherein the latch is movable between a blocking configuration of said carriage in an intermediate position of the latter, and a release configuration of said carriage in which it is free to slide along the translation guide to a second position thereof with a movement opposite that of the first leaf carriage; and wherein i) when the first carriage is in the first position, said means (10, 12) are mutually coupled to keep the latch in the release configuration, in contrast to the action of the return means; ii) when the carriage is in the intermediate position (Fig. 4), said means (10, 12) are uncoupled so that the latch is moved by the return means to the blocking configuration; and wherein - the latch and the first leaf carriage comprise first complementary engagement elements (14, 16) which in the blocking configuration cooperate by shape and/or by force to carry out said blocking, and which in the release configuration do not interact with each other or lie mutually spaced in a transverse or orthogonal direction with respect to the sliding direction; - the latch 6 and the second leaf carriage 4' comprise second complementary engagement elements 38, 40, which, in the blocking configuration, cooperate by shape and/or by force to carry out the aforesaid blocking, and which, in the release configuration, do not interact with each other or lie mutually spaced, e.g., in a transverse T or orthogonal direction with respect to the sliding direction X.