Gomis scored a hat-trick in the 4-1 win at Marseille in midweek to fire Lyon to the top of the table before they host champions Montpellier and PSG travel to improving Nice on Saturday.
Lyon have 28 points from 14 games and lead PSG by two points with OM third behind the capital side on goal difference.
"Both clubs (Lyon and OM) are in the title race to compete with Paris," Gomis told reporters.
PSG spent around 150 million euros on transfers in the off-season, including the signing of Swede Ibrahimovic, while OM and Lyon spent just over 10 million between them.
PSG's football has been far from impressive this season and they have been heavily relying on Ibrahimovic, who has scored 12 goals in 11 league appearances.
"On paper, Ancelotti has the best team, the best squad. But it does not fall into place in the twinkling of an eye," France coach Didier Deschamps, told BeIN Sport TV last week.
Lyon's game, instead, is more collective.
"Our strength is to make our opponents run by playing one-touch football," said midfielder Maxime Gonalons.
However, Lyon know they will not have everything their own way after being beaten 3-0 at Toulouse last Sunday.
"Everything goes fast. We host Montpellier and if we are not careful, the Toulouse accident can happen again," said Gomis.
Fourth-placed St Etienne, who eliminated PSG on penalties in the League Cup quarter-finals on Tuesday, can take the Ligue 1 lead when they play Ajaccio on Friday.
Coach Christophe Galtier is hopeful his players will have recuperated after playing 120 minutes against PSG.
"We're struggling physically, but when you win, you recuperate faster," he told reporters.
Whatever happens, second from bottom Troyes, who host Stade Rennes on Sunday, and basement side Nancy, who travel to Evian Thonon Gaillard, will stay in the relegation zone.
They trail 17th-placed Evian by seven and eight points respectively.