The present invention relates to an engine assembly for an aircraft comprising an attachment means, a turboprop on an attachment mast, this means including a plurality of front engine attachments (16) each having an engine vibration insulation system (20) including a housing (22), a stress transmitting member (24) extending along a first axis (26) parallel to an axis of rotation of the propeller and a hollow member (28) integrated in the housing and extending along a second axis (30) orthogonal to and intersecting the first axis. According to the invention, a support means for supporting the system (20) is formed by a plurality of clevises (32a, 32b) each having a middle plane parallel to its clevis heads, integrating one of the first and second axes and orthogonal to the other of said axes.