Unfortunately, yes. Pact of the Blade makes you proficient with the weapon, but doesn't negate the Heavy property, so you'd still need a 13 in Strength to wield it without disadvantage on attack rolls.
Edit: Completely missed the '2014' bit. My bad. Same answer applies, but the penalty is different.
When I conjure Great Sword as pact of blade in D&D 2014 Version
does it need strength atleast 13 to wield it or not?
Unfortunately, yes. Pact of the Blade makes you proficient with the weapon, but doesn't negate the Heavy property, so you'd still need a 13 in Strength to wield it without disadvantage on attack rolls.
Edit: Completely missed the '2014' bit. My bad. Same answer applies, but the penalty is different.